MD Lorene Zerah
email: lorene.zerah@aphp.fr

Jacques Boddaert

PhD Armelle Leperre-Desplanques

MD Dominique Bonnet-Zamponi

MD Marc Verny

PhD Jean Deligne

Pierre-Yves Boelle

Hospitalizations in Elderly People Treated for Dementia: A Self-Controlled Case Series Study Based on the Matching of 2 French Health Insurance Databases

Keywords: Adverse Drug Event, PFC: Proportional Fold Change, IA: Iatrogenic Alert Iatrogenic alert, Adverse drug event, Self-controlled analysis Running Title: Adverse drug hospitalizations and dementia

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INTRODUCTION

Demographic ageing is associated with an increase in repeated hospital admissions [START_REF] Kirby | Patient related factors in frequent readmissions: the influence of condition, access to services and patient choice[END_REF][START_REF] Jencks | Rehospitalizations among Patients in the Medicare Fee-for-Service Program[END_REF][START_REF] Bottle | Identifying patients at high risk of emergency hospital admissions: a logistic regression analysis[END_REF].

Reducing these hospitalizations is a priority for hospitals and national health plans.

Identifying the modifiable factors that are associated with the risk of hospital admission in elderly people is of a major interest with the aim of conceiving risk minimization strategies.

Five to 20% of all hospital admissions are known to be related to Adverse Drug Events (ADE) in people aged 65 [START_REF] Budnitz | Emergency hospitalizations for adverse drug events in older Americans[END_REF][START_REF] Beijer | Hospitalisations caused by adverse drug reactions (ADR): a meta-analysis of observational studies[END_REF][START_REF] Gurwitz | Incidence and preventability of adverse drug events among older persons in the ambulatory setting[END_REF][START_REF] Budnitz | National surveillance of emergency department visits for outpatient adverse drug events[END_REF] and over 40 to 70% of these ADE-related admissions would be preventable [START_REF] Gurwitz | Incidence and preventability of adverse drug events among older persons in the ambulatory setting[END_REF][START_REF] Franceschi | Prevalence, clinical features and avoidability of adverse drug reactions as cause of admission to a geriatric unit: a prospective study of 1756 patients[END_REF][START_REF] Pirmohamed | Adverse drug reactions as cause of admission to hospital: prospective analysis of 18 820 patients[END_REF]. This has prompted the development of criterion-based tools (explicit measures) to assess and correct inappropriate prescription in elderly people [START_REF] Laroche | Potentially inappropriate medications in the elderly: a French consensus panel list[END_REF][START_REF] Spinewine | Appropriate prescribing in elderly people: how well can it be measured and optimised[END_REF][START_REF] Gallagher | Screening Tool of Older Person's Prescriptions) and START (Screening Tool to Alert doctors to Right Treatment). Consensus validation[END_REF][START_REF]The American Geriatrics Society 2012 Beers Criteria Update Expert Panel. American Geriatrics Society updated Beers Criteria for potentially inappropriate medication use in older Adults[END_REF][START_REF] Price | Association between potentially inappropriate medications from the Beers Criteria and the risk of unplanned hospitalization in elderly patients[END_REF][START_REF] Price | Impact of specific Beers Criteria medications on associations between drug exposure and unplanned hospitalisation in elderly patients taking high-risk drugs: A case-time-control study in Western Australia[END_REF]. However, the evidence that inappropriate prescription, as defined by explicit measures, is associated with adverse patient outcomes and notably hospitalizations, is mixed and contradictory [START_REF] Spinewine | Appropriate prescribing in elderly people: how well can it be measured and optimised[END_REF][START_REF] Taylor | Application of the STOPP/START criteria: a systematic review of the prevalence of potentially inappropriate prescribing in older adults, and evidence of clinical, humanistic and economic impact[END_REF][START_REF] Hanlon | What types of inappropriate prescribing predict adverse drug reactions in older adults?[END_REF]. This could be explained by a too extensive approach of the appropriateness of the prescription inasmuch as these tools are concerned (the risk for serious ADE varying widely from a criterion to another in the context of the same tool) and/or a study population running a too heterogeneous risk for hospitalization.

In 2011, with a view to managing national health plan in order to improve medication in elderly people, the French National Authority for Health requested a panel of French health professionals to determine the most prominent criteria regarding cardiovascular and psychotropic drugs known to be involved in ADE-related admissions [START_REF] Budnitz | Emergency hospitalizations for adverse drug events in older Americans[END_REF][START_REF] Beijer | Hospitalisations caused by adverse drug reactions (ADR): a meta-analysis of observational studies[END_REF][START_REF] Gurwitz | Incidence and preventability of adverse drug events among older persons in the ambulatory setting[END_REF][START_REF] Budnitz | National surveillance of emergency department visits for outpatient adverse drug events[END_REF][START_REF] Pirmohamed | Adverse drug reactions as cause of admission to hospital: prospective analysis of 18 820 patients[END_REF][START_REF] Laroche | Potentially inappropriate medications in the elderly: a French consensus panel list[END_REF][START_REF] Spinewine | Appropriate prescribing in elderly people: how well can it be measured and optimised[END_REF][START_REF] Gallagher | Screening Tool of Older Person's Prescriptions) and START (Screening Tool to Alert doctors to Right Treatment). Consensus validation[END_REF][START_REF] Price | Association between potentially inappropriate medications from the Beers Criteria and the risk of unplanned hospitalization in elderly patients[END_REF][START_REF] Price | Impact of specific Beers Criteria medications on associations between drug exposure and unplanned hospitalisation in elderly patients taking high-risk drugs: A case-time-control study in Western Australia[END_REF][START_REF] Huang | Medication-related falls in the elderly[END_REF].

According to literature data and its clinical practice, five "Iatrogenic Alerts" (IAs) were finally found to be easy to assess and clinically relevant to prevent serious ADE in the elderly [START_REF]Prescription Médicamenteuse chez le Sujet Agé (PMSA) -Programme Pilote 2006-2013[END_REF]. There were 3 psychotropic IAs corresponding to [START_REF] Kirby | Patient related factors in frequent readmissions: the influence of condition, access to services and patient choice[END_REF] the prescription of a long half-life benzodiazepine; (2) the prescription of antipsychotic drugs in Alzheimer patients; and (3) the co-prescription of 3 or more psychotropic drugs; and 2 cardiovascular IAs with (4) the co-prescription of 2 or more diuretics and (5) the co-prescription of 4 or more antihypertensive drugs.

The aim of our study is to validate this new screening tool of inappropriate prescriptions in elderly people, by measuring the association between these IAs and the risk of hospitalizations. We focused on patients treated for dementia because they have a high risk for hospitalizations and because one of the IA is specific to this population [START_REF]Prescription Médicamenteuse chez le Sujet Agé (PMSA) -Programme Pilote 2006-2013[END_REF][START_REF] Oyarzun-Gonzalez | Cognitive decline and polypharmacy in an elderly population[END_REF][START_REF] Gnjidic | Impact of high risk drug use on hospitalization and mortality in older people with and without Alzheimer's disease: a national population cohort study[END_REF][START_REF] Lau | Functional decline associated with polypharmacy and potentially inappropriate medications in community-dwelling older adults with dementia[END_REF].

Our main objective was to examine the association between hospitalizations, whatever their leading cause, and IAs in elderly people treated for dementia, using a self-controlled case series design. Second, we examined the association between the potentially ADE-related hospitalizations and the IAs.

METHODS

A two-year longitudinal national database study using an approach similar to the "selfcontrolled case series" [START_REF] Petersen | Self controlled case series methods: an alternative to standard epidemiological study designs[END_REF][START_REF] Whitaker | The methodology of self-controlled case series studies[END_REF] between January 1, 2011 and December 31, 2012 was set up.

The study is reported according to the RECORD recommendation [START_REF] Benchimol | The REporting of studies Conducted using Observational Routinely-collected health Data (RECORD) Statement[END_REF]. It was divided into 4 consecutive six-month periods allowing the sequential analysis in the case of each patient based on a moderate amount of data. Indeed, a monthly analysis would have produced 24 one-month periods for each patient making the analysis more complex with little benefit.

Conversely, an annual analysis, with only 2 one-year periods for each patient would not have made possible a detailed analysis. The 6-month analysis seemed a good compromise to us.

Databases

Data were obtained from 2 French National Health Insurance Databases. The RSI' database ("Régime Social des Indépendants" -social scheme for the self-employed) included data from 6 million self-employed people, such as age, sex, social security numbers, all ambulatory prescriptions and the prescriber and all hospitalizations in private hospitals (with Major Diagnosis Category (MDC), corresponding to the leading cause of hospital admission [START_REF]Employment and Health. Manuel des Groupes Homogènes de Malades[END_REF], Appendix 1). The SNIIRAM' database ("Système National d'Information Inter-Régimes de l'Assurance Maladie" -The French National Health Insurance Information System) which collects all individualized and anonymous healthcare claims reimbursed by the French National Health Insurance covering the entire French population [START_REF] Tuppin | French national health insurance information system and the permanent beneficiaries sample[END_REF]. In addition, this database contains patient data such as sex, vital status and eligibility for a 100% health insurance coverage for serious and costly long-term diseases (LTDs), encoded in the International Classification of Diseases, 10 th revision (ICD 10) ( 28) and all hospitalizations in public hospital with their MDC [START_REF]Employment and Health. Manuel des Groupes Homogènes de Malades[END_REF].

Population selection (figure 1)

All affiliates of the RSI aged 75 years or more on January 1 st , 2011 with a diagnosis of dementia and undergoing a specific treatment, were included. "Dementia with a specific treatment" was defined by the WHOs ICD-10 code "Alzheimer's disease" (F00-F03*) [START_REF]Employment and Health. Manuel des Groupes Homogènes de Malades[END_REF] and by the prescription of a drug for Alzheimer disease (ATC "Anatomical Therapeutic Chemical » code NO6D [START_REF]Guidelines for ATC Classification and DDD Assignment[END_REF]. All patients undergoing a specific treatment had an ICD-10 code. The Charlson comorbidity index (CCI) was calculated for each patient (missing information was replaced by the default -least severe -value, see Appendix 2) [START_REF]International Statistical Classification of Diseases and Related Health Problems 10th Revisions[END_REF][START_REF] Sundararajan | Cross-national comparative performance of three versions of the ICD-10 Charlson index[END_REF][START_REF] Quan | Updating and validating the Charlson comorbidity index and score for risk adjustment in hospital discharge abstracts using data from 6 countries[END_REF].

Databases matching (figure 1)

SNIIRAM' and RSI databases have restricted access according to privacy laws [START_REF] Tuppin | French national health insurance information system and the permanent beneficiaries sample[END_REF]. We obtained the authorization to match the 2 databases anonymously. In the absence of a unique patient identifier, the matching of the 2 databases was performed based on such criteria as sex, the year of birth, the social security number, the prescriber and the specific Alzheimer's drugs refunded during the first 6-month period (inclusion criteria). Authorizations were obtained in respect of the French regulations (CNIL authorization n° 1537081).

Exposure

For each drug delivery, the ATC class of the prescribed drug was available with a precision ranging from 3 to 5 digits [START_REF]Guidelines for ATC Classification and DDD Assignment[END_REF].

We determined, for each patient and for each six-month period:

-the presence of an IA: the algorithm for identifying IAs is described in Appendix 3 [START_REF]Prescription Médicamenteuse chez le Sujet Agé (PMSA) -Programme Pilote 2006-2013[END_REF].

It was developed from the ATC codes proposed by French National Authority for Health.

The co prescription IAs was defined by the delivery of 2 or more different drugs over the course of the same six-month period.

-the delivery of a drug known to increase the risk of ADE-related hospitalization and not included in IAs (4,6): we included antiplatelet agents or anticoagulants (ATC: B01); Nonsteroidal anti-inflammatory drug (NSAID) (ATC: M01); oral antidiabetic drugs (OADs) and insulin (ATC: A10); Digoxin (ATC: C01AA05).

-the occurrence of polypharmacy. This was the case when at least five drugs with different ATC codes were delivered during the same six-month period [START_REF] Budnitz | Emergency hospitalizations for adverse drug events in older Americans[END_REF][START_REF] Gurwitz | Incidence and preventability of adverse drug events among older persons in the ambulatory setting[END_REF][START_REF] Wallace | Appropriate prescribing and important drug interactions in older adults[END_REF].

Outcomes: Hospitalizations and Major Diagnosis Categories (MDC)

The number of hospitalizations over a six-month period was calculated for each patient.

Patients who had more than 10 hospitalizations during the same six-month period (N = 34corresponding to chemotherapy, dialysis, reeducation sessions; Figure 1) were excluded because these repeated hospitalizations were planned and not related to IAs.

The main outcome was the rate of all hospitalizations, whatever their leading cause.

For a more detailed second analysis, according to our clinical experience and the literature [START_REF] Budnitz | Emergency hospitalizations for adverse drug events in older Americans[END_REF][START_REF] Gurwitz | Incidence and preventability of adverse drug events among older persons in the ambulatory setting[END_REF][START_REF] Franceschi | Prevalence, clinical features and avoidability of adverse drug reactions as cause of admission to a geriatric unit: a prospective study of 1756 patients[END_REF][START_REF] Pirmohamed | Adverse drug reactions as cause of admission to hospital: prospective analysis of 18 820 patients[END_REF][START_REF] Price | Association between potentially inappropriate medications from the Beers Criteria and the risk of unplanned hospitalization in elderly patients[END_REF][START_REF] Price | Impact of specific Beers Criteria medications on associations between drug exposure and unplanned hospitalisation in elderly patients taking high-risk drugs: A case-time-control study in Western Australia[END_REF][START_REF] Huang | Medication-related falls in the elderly[END_REF][START_REF] Voisin | Descriptive analysis of hospitalizations of patients with Alzheimer's disease: a two-year prospective study of 686 patients from the REAL.FR study[END_REF][START_REF] Butt | Benefits and risks of antihypertensive medications in the elderly[END_REF], we analyzed the association between IAs and the risk of hospitalization, according to 3 pre-specified relevant MDC groups defined as "context", "potentially ADE-related" and "other" (Table 1).

-"Context" hospitalizations: hospitalizations the leading cause of which (MDC) was linked to a decompensated disease that could have led to the initial delivery of an IA. More precisely, this included "Diseases and Disorders of the nervous system" (MDC1) and "Mental Diseases and Disorders" (MDC19) for the 3 psychotropic IAs and "Diseases of the respiratory / circulatory system" (MDC 4/5) for the cardiovascular IAs.

-"Potentially ADE-related" hospitalizations were those compatible with ADE occurring with cardiovascular or psychotropic drugs. We included in this category hospitalizations related to "Trauma, allergies, poisoning" (MDC 8, 20, 21).

-All other MDCs were classified in the "Other" category, with hospitalizations that were a priori unrelated to the cardiovascular and psychotropic drugs (initial delivery or leading cause of hospital admission): eye/ear/throat diseases (MDC2 and 3), tumors (MDC16-17), infectious diseases (MDC18)), digestive, hepatobiliary and pancreas system (MD6 and MD7); skin, subcutaneous tissue and breast (MD9); endocrine, nutritional and metabolic system (MD10); kidney and urinary tract (MDC11).

However, some hospitalizations classified in "context" and "others" categories may be "potentially ADE-related" hospitalizations. Since the codes did not allow us to define it with certainty, we had chosen to classify only traumatic and poisoning hospitalizations in potentially ADE-related hospitalizations ("minimalist" approach).

STATISTICAL ANALYSES

The association of each IA with hospitalizations (self-adjusted proportional fold change (PFC)) was investigated separately for all hospitalizations (whatever the leading cause) and then for the 3 pre-specified categories (context, potentially ADE-related, other). Analyses were also done for the occurrence of polypharmacy and other drugs of interest.

We used an approach similar to the "self-controlled case series" (23,24) (epidemiological study design for which individuals act as their own controls) to jointly analyze the number of hospitalizations throughout the six-month periods spanning each patient's follow-up, comparing each patient to themselves in a different period. Periods without an IA served as a control for periods with an IA for the same patient: the ratio of hospitalizations was determined by considering the 6-month periods where an IA was present ("at risk" periods) and the others ("non-risk" periods). Patients who had never been hospitalized over a period of 2 years did not provide any information to this analysis. Patients who either had a permanent IA or none throughout the four 6-month periods contributed to the estimation of the specific effect of the period. Patients who died during the study period were analyzed except for the final 6-month period of their life, as changes in prescription could occur in terminally ill people. For all statistical analysis, we used the statistical software R (version 3.1.0) with package multinomRob (http://CRAN.R-project.org/package=multinomRob). The details of the statistical analysis are described in appendix 4.

RESULTS

Population

The average age of the population was 85 (± 5.0), the majority of them being women (61%).

The average CCI was 5.5 (± 1.0), with a large prevalence of cardiovascular diseases in 29% (hypertension, diabetes, heart failure, coronary failure, atrial fibrillation), neuropsychiatric diseases in 10% (Parkinson's disease, stroke, depression) and cancer in 12%. Over the span of 2 years, 2196 individuals died (death rate 10% per year). Patients who were hospitalized at least once had more comorbidities (1.0 ± 0.9 vs. 0.8 ± 0.8, p <0.001) and more medications (polypharmacy: 90.3% vs. 88.4%, p <0.0001) than patients never hospitalized, with no difference with age. The description of the population is summarized in table 2.

Exposure to Iatrogenic Alerts

At least one IA was present in 35% of all six-month periods, psychotropic IAs were more common (30% of periods) than cardiovascular IAs (9% of periods). The prevalence of IAs per 6-month periods in the population was: 16.5% for IA antipsychotic drugs, 15.5% for IA ≥ 3 psychotropic drugs, 9.7% for IA long half-life benzodiazepine, 5.9% for IA ≥ 2 diuretics, 5.4% for IA ≥ 4 antihypertensive drugs (table 2). Patients could present several IAs in the same period, but there was no correlation between the presence of psychotropic and cardiovascular IAs (P=0.52).

Hospitalizations

The average number of hospitalizations for a six-month period was 0.27, with a slight decreasing trend over time from 0.31 in early 2011 to 0.24 in late 2012. The average number of hospitalizations for a six-month period decreased with age, from 0.29 in the 75-80 years old to 0.26 in the >90 years old and increased with the CCI index, from 0.27 (CCI ≤ 7) to 0.38 (CCI > 7). Patients who were hospitalized at least once had more IAs (Long half-life benzodiazepine: 10.3% vs. 8.8%, p < 0.0001; Antipsychotic: 17.5% vs. 15.3%, p < 0.0001; ≥ 3 psychotropic drugs: 17.6% vs. 13%, p < 0.0001; ≥ 2 diuretics: 6.5% vs. 5.1%, p < 0.0001; ≥ 4 antihypertensive drugs: 6.1% vs. 4.4%, p < 0.0001), more polypharmacy (90.3% vs. 88.4%, p <0.0001), more antiplatelet and anticoagulant drugs (55.8% vs. 44.5%, p <0.0001), more oral antidiabetic agents and / or insulin (12.1% vs. 10.6%, p = 0.002) and more digoxin (4.4% vs. 3.5%, p <0.0001) than patients never hospitalized (table 2).

Outcomes

Association between hospitalization rate and IAs

On average, there were 0.23 hospitalizations over a period of six months without IAs vs. 0.36 when at least one IA was present. The self-controlled analysis showed that the number of hospitalizations was double for periods with an IA relative to others periods (PFC 1.9, CI95% [1.8, 2.1]), with PFC ranging from 1.7 [1.5, 1.8] to 2.1 [1.8, 2.3] depending on the IA type.

We calculated that 22% (CI95% [20%, 23%]) of all hospitalizations were associated to IAs, the 80% of which were due to psychotropic IAs. All results are shown in table 3.

Association between potentially ADE-related admissions and IAs

"Context" hospitalizations represented 28% of all hospitalizations and "potentially ADErelated" represented 18% of all hospitalizations. The impact of IAs changed with the type of hospitalization (Figure 2, Table 3): the largest increase occurred for the "context" hospitalizations (with PFC between 2.2 [1.8, 2.8] and 3.0 [2.6, 3.4] in the presence of an IA);

for "potentially ADE-related" hospitalizations the PFC ranged between 1.3 [0.8, 1.9] and 2.2 [1.8, 2.7]; and it ranged between 1.3 [1.1, 1.5] and 1.8 [1.6, 2.1] for "other" hospitalizations.

We calculated that 17% of "potentially ADE-related" hospitalizations were associated to psychotropic IAs and 4% to cardiovascular IAs: this amounted, respectively, to 3% (=17% * 18%) and 1% (=4%*18%) of all hospitalizations. antiplatelet drugs, oral anti-diabetic / insulin drugs, NSAID and digoxin) showed the validity of our analysis.

Association between hospitalization rate and other drugs

We found an association between inappropriate prescribing as defined by the IAs [START_REF]Prescription Médicamenteuse chez le Sujet Agé (PMSA) -Programme Pilote 2006-2013[END_REF] and hospitalizations in a large sample of older people treated for dementia, unlike the usual sets of explicit criteria focused on misuse and overuse [START_REF] Taylor | Application of the STOPP/START criteria: a systematic review of the prevalence of potentially inappropriate prescribing in older adults, and evidence of clinical, humanistic and economic impact[END_REF][START_REF] Wauters | Too many, too few, or too unsafe? Impact of inappropriate prescribing on mortality, and hospitalization in a cohort of community-dwelling oldest old[END_REF][START_REF] Johansson | Impact of strategies to reduce polypharmacy on clinically relevant endpoints: a systematic review and metaanalysis[END_REF]. This could be explained first by the clinical relevance of the IAs. Indeed, the IAs do not encompass large number of drugs known to be inappropriate in elderly but are restricted to drugs of two classes known to be highly implicated in severe ADE in Western countries (4-7,9-15,18). Moreover, the IAs are mainly focused on the duplication of these drug classes, and so detect only prescribing with very high risk for ADE. Second, the choice of a study population both with high risk of inappropriate psychotropic exposure and of ADE could have facilitated the detection of this association. Interestingly, recent study from a longitudinal cohort found also an association between inappropriate drug use and hospitalizations in a population closed to ours (people with dementia according to DSM-III-R criteria) [START_REF] Sköldunger | Impact of Inappropriate Drug Use on Hospitalizations, Mortality, and Costs in Older Persons and Persons with Dementia: Findings from the SNAC Study[END_REF]. Criteria defining inappropriate drug use in this study cross-referenced psychotropic IAs (use of 3 or more psychotropic drugs, use of long-acting benzodiazepines), suggesting that psychotropic IAs could be pertinent also in people suffered from dementia, with or without treatment. However, further studies are needed to explore the association between the whole of IAs and hospitalizations in patients with dementia whatever their treatment and in older population whatever their diseases.

Moreover, the association between IAs and hospitalizations need also to be further studied to better understand if IAs are causes and/or consequences and/or independent markers of the risk of hospitalizations. Interventions studies assessing the impact of reduction of the IAs on hospitalizations rate would be especially desirable.

Strengths of the study

We chose to use an approach similar to the "self-controlled case series" [START_REF] Petersen | Self controlled case series methods: an alternative to standard epidemiological study designs[END_REF][START_REF] Whitaker | The methodology of self-controlled case series studies[END_REF], built on the change in exposure over time in the same patient, to reduce the bias of confusion. Indeed, it is well known that adjusting to differences between patients, besides the exposure of interest, is required in the analysis of observational data. This is why, comparing each patient to themselves is "the ultimate form of adjustment" [START_REF] Louis | Crossover and self-controlled designs in clinical research[END_REF]. It automatically takes into account factors associated with hospitalization among the elderly: marital status, education, autonomy, place of living, tobacco or alcohol use [START_REF] Budnitz | Emergency hospitalizations for adverse drug events in older Americans[END_REF][START_REF] Gurwitz | Incidence and preventability of adverse drug events among older persons in the ambulatory setting[END_REF][START_REF] Price | Association between potentially inappropriate medications from the Beers Criteria and the risk of unplanned hospitalization in elderly patients[END_REF][START_REF] Price | Impact of specific Beers Criteria medications on associations between drug exposure and unplanned hospitalisation in elderly patients taking high-risk drugs: A case-time-control study in Western Australia[END_REF]. This was particularly relevant as such data are not available in databases primary purpose of which is either administrative or compensation [START_REF] Tuppin | French national health insurance information system and the permanent beneficiaries sample[END_REF]. An additional feature was the inclusion of patients who either had an IA or not in the four 6-month periods under study, as it allowed further adjustment in hospitalization rates over time (estimation of the period specific effect), for example due to seasonal changes (winter /summer).

Limits of the study

The population under study differed from the general elderly population with dementia in several aspects. First, it included only patients treated for dementia. To match the 2 databases (RSI and SNIIRAM) we had to exclude people without treatment (and 1408 patients with database matching unsuccessful). It is known that these patients are at greater risk of hospitalizations than the others and take more medications [START_REF] Oyarzun-Gonzalez | Cognitive decline and polypharmacy in an elderly population[END_REF][START_REF] Gnjidic | Impact of high risk drug use on hospitalization and mortality in older people with and without Alzheimer's disease: a national population cohort study[END_REF][START_REF] Lau | Functional decline associated with polypharmacy and potentially inappropriate medications in community-dwelling older adults with dementia[END_REF]. This could lead to increased hospitalization rates compared to the rest of the elderly population with dementia and increased prevalence of IAs. Second, the sample was selected from retired self-employed persons (RSI' database), limiting the relevance of the population. However, the population of the study benefits from the same general practitioners and hospitals as the rest of the population, so eventually this should not affect the results.

For our secondary analysis, defining causes of hospitalizations that are likely due to ADEs was a difficult task without proper coding. For example, epilepsy might be related to psychotropic side effects, acute renal failure to diuretics, and so on. We adopted a "minimalist" approach, considering only poisoning and trauma as "potentially ADE-related" and more likely to be affected by change in prescriptions. The maximum impact of reducing the prevalence of the IAs is therefore likely to be in the range defined by the "avoidable part" (3% of all hospitalizations) and the "attributable part" (22% of all hospitalizations).

Finally, the analysis of six-month periods could have led to the categorization of periods with sequential prescription of several drugs as periods when a combination of drugs was present, increasing the occurrence of periods with an IAs. However, this condition should only lead to underestimating the strength of association of IAs with hospitalization; it should not challenge our results. A last aspect of this grouping is that it was not possible to tell whether the iatrogenic alert took place before, during or after the hospitalization within the same semester.

CONCLUSION

The present study provides the first evaluation of the association between IAs and hospitalizations. We showed that the risk of hospitalization nearly doubled in elderly patients in treatment for dementia when they were exposed to psychotropic and/or cardiovascular Iatrogenic Alerts. These Iatrogenic Alerts, resulting from a selection of existing explicit criteria by French experts, are a promising simple way of reducing serious ADE in this vulnerable population. Interventional studies are now needed to explore if the reduction of theses IAs can be associated with better clinical outcomes and notably with reduction of hospital admissions.

  Periods of six months in polypharmacy patients were associated with a large increase of all hospitalization causes (proportional fold change, PFC: 3.6 [3.2, 4.0]), with hospitalizations for "Endocrine, Nutritional & Metabolic System" (MDC10) increasing the most (PFC=10.1 [3.8, 26.5]). A similar increase was observed in periods of use of anticoagulant / antiplatelet drugs (overall proportional fold change: 3.2 [2.9, 3.5]), NSAID (proportional fold change: 1.3 [1.2, 1.4]), oral anti-diabetic / insulin drugs (proportional fold change: 1.7 [1.4, 2.1]) and digoxin (proportional fold change: 1.7 [1.4, 2.1]). The largest increase of MDCs hospitalization changed according to the drugs was: "Circulatory System" (MDC5 -PFC 5.6 [4.5, 7.0]) for anticoagulants, "Kidney And Urinary Tract" (MDC11 -PFC=1.6[1.1, 2.5]) for NSAID, "Endocrine, Nutritional & Metabolic System" (MDC10 -PFC = 5.8 [2.4, 13.9]) for oral antidiabetic drugs and "Respiratory system" (MDC4 -PFC = 2.6 [1.5, 4.7]) for digoxin.

• FIGURE 1: Flow Chart of patient selection from Health Insurance databases. • TABLE 1: Classification of hospitalization with Major Diagnostic Categories (MDC) by relevance with Cardiovascular and Psychotropic drug prescriptions • TABLE 2: Patients characteristics and Iatrogenic Alerts • TABLE 3: Proportional Fold Change in the number of hospitalizations per six- month period by iatrogenic alert and hospitalization type. • FIGURE 2: Proportional Fold change in the number of hospitalizations (using Major Diagnostic Categories) per six-month period with the presence of an IA (Iatrogenic Alert) Psychotropic IAs** Cardiovascular IAs** Leading primary cause of hospitalization By major diagnosis categories (MDC*)

  More precisely, we assumed that the number H ij of hospitalizations in patient i and six-month period j had average 𝜆𝜆 𝑖𝑖 exp�𝛽𝛽 𝐴𝐴𝐴𝐴 𝑎𝑎 𝑖𝑖𝑖𝑖 + 𝛽𝛽 𝑖𝑖 � where 𝜆𝜆 𝑖𝑖 was a patient specific rate -including the effect of all factors that do not change significantly over 2 years' time (sex, age, …), 𝛽𝛽 𝑖𝑖 was a (6-month) period specific effect adjusting for time trends in hospitalization and 𝛽𝛽 𝐴𝐴𝐴𝐴 was the IA specific effect of interest (a ij = 1 if an IA occurs in period j for patient i). The coefficient PFC = exp(𝛽𝛽 𝐴𝐴𝐴𝐴 ) quantifies the self-adjusted proportional fold change (PFC) in the number of hospitalizations over a 6-month period depending if an IA is present. Conditionally on the total number of hospitalizations, the joint distribution of (H 1i , H i2 , H i3 , H i4 ) was multinomial with parameters�exp�𝛽𝛽 𝐴𝐴𝐴𝐴 𝑎𝑎 𝑖𝑖𝑖𝑖 + 𝛽𝛽 𝑖𝑖 � ∑ exp(𝛽𝛽 𝐴𝐴𝐴𝐴 𝑎𝑎 𝑖𝑖𝑖𝑖 + 𝛽𝛽 𝑖𝑖 ) ≤ 4, where the patient-specific rate of hospitalization 𝜆𝜆 𝑖𝑖 had been cancelled out and was not estimated. Finally, we calculated the population-level fraction of hospitalizations attributable to an iatrogenic alert as 𝐴𝐴𝐴𝐴 = ∑ ℎ 𝑖𝑖𝑖𝑖 �1 -𝑒𝑒𝑒𝑒𝑒𝑒�-𝛽𝛽 𝐴𝐴𝐴𝐴 𝑎𝑎 𝑖𝑖𝑖𝑖 ��

	Overall APPENDIX 1: Major Diagnostic Categories (MDC) APPENDIX 4: Statistical analysis	Hospitalization Hospitalization type	P-value
	CTXT   Never N = 4396 Context AR ADE 85.1 ± 5.1 2.3 [1.9, 2.7] N = 10754 AR PFC 1.95 [1.8, 2.1] 22% All PFC Nervous system 85.0 ± 5.0 1.65 [1.5, 1.8] 5% 8% Eye 61% 66% 1.79 [1.7, 1.9] 9% 2.7 [2.4, 3.1] 23% 2.04 [1.9, 2.2] 12% 3.0 [2.6, 3.4] 16% Ear, Nose, Mouth And Throat Charlson index (mean ± SD) Nervous system (1) Mental Diseases and Disorders (19) Respiratory System (4) Circulatory System (5) Iatrogenic Alerts Any MDC 1 Age (years, mean ± SD) Long half-life benzodiazepine MDC2 Sex (% Female) Antipsychotic in Alzheimer patients ≥ 3 psychotropic drugs MDC3 5.5 ± 1.0 5.4 ± 0.9 ≥ 2 diuretics 1.73 [1.5, 2.0] 3% 2.2 [1.8, 2.8] 5% MDC4 Respiratory System Comorbidities (mean ± SD) 0.9 ± 0.9 0.8 ± 0.8 Parkinson disease 5.2% 4.3% ≥ 4 antihypertensive drugs 2.08 [1.8, 2.3] 5% 2.8 [2.3, 3.4] 6% MDC5 Circulatory System PFC: Proportional Fold Change, AR = Attributable ratio MDC6 Digestive System ADE: adverse drug event Musculoskeletal System And Connective Tissue (8)  Depression 0.4% 0.2 % MDC7 Hepatobiliary System And Pancreas Alcohol/Drug Use or Induced Mental Disorders (20)  Arterial hypertension 11.3% 11.0% MDC8 Musculoskeletal System And Connective Tissue OTHR   Potentially ADE-related CTXT ADE  Once or more PFC AR N = 6358 85.0 ± 5.0 1.7 [1.3, 2.3] 6% 0.40 58% 2.1 [1.7, 2.5] 19% 2.2 [1.8, 2.7] 13% <0.001  OTHR  PFC 1.3 [1.1, 1.5] Other 1.5 [1.4, 1.7] 1.6 [1.4, 1.8] 5.5 ±1.0 1.3 [0.8, 1.9] 2% 1.6 [1.3, 1.9] <0.001 1.0 ± 0.9 <0.001 5.8% 0.001 1.4 [1.0, 2.0] 3% 1.8 [1.6, 2.1]  0.5% 0.02  11.6% 0.28  Injuries, Poison And Toxic Effect of Drugs (21)  Diabetes 11.0% 10.0% 11.8% MDC9 Skin, Subcutaneous Tissue And Breast 0.003  Eye (2)   Ear, Nose, Mouth And Throat (3)   Digestive System (6)   Hepatobiliary System And Pancreas (7)  Atrial fibrillation Heart failure Cancer 4.4% 4.3% 11.5 % 3.5% 3.5% 9.6% 5.1% 4.9% 13.0% 0.001 0.006 <0.001 Death (%) * 4.6% 3.1% 5.7% <0.001 MDC10 Endocrine, Nutritional And Metabolic System MDC11 Kidney And Urinary Tract MDC12 Male Reproductive System MDC13 Female Reproductive System 4 𝑖𝑖=1 ⁄ � for 1 ≤ j 𝑖𝑖,𝑖𝑖 ∑ ℎ 𝑖𝑖𝑖𝑖 𝑖𝑖,𝑖𝑖 � , i.e. the fraction  Skin, Subcutaneous Tissue And Breast (9)   Endocrine, Nutritional And Metabolic System (10)  Kidney And Urinary Tract (11)  Infectious and Parasitic Diseases & Disorders (18)  Oral anti-diabetic / Insulin 11.4% 10.6% 12.1% MDC23 Factors Influencing Health Status 0.002 ** CTXT: Context; ADE: potentially ADE related; OTHR: Other. NSAID 9.6% 9.5% 9.7% MDC22 Burns 0.15 MDC27 (organ transplants), MDC 28 and 90 (Errors and other unclassifiable stays) were not present in the database Anticoagulant / Antiplatelet 51.0% 44.5% 55.8% MDC21 Injuries, Poison And Toxic Effect of Drugs <0.0001 * MDC 12-15 (reproduction & newborns), 22-25 (Burns, Multiple Trauma, HIV), MDC 26 (Severe multiple trauma), MDC20 Alcohol/Drug Use or Induced Mental Disorders Other drugs (%) *  ≥ 4 antihypertensive drugs 5.4% 4.4% 6.1% <0.0001 MDC19 Mental Diseases and Disorders Poorly Differentiated Neoplasms (17)   ≥ 2 diuretics 5.9% 5.1% 6.5% <0.0001 MDC18 Infectious and Parasitic DDs Blood and Blood Forming Organs and Immunological Disorders (16)   ≥ 3 psychotropic drugs 15.5% 13.0% 17.6% <0.0001 MDC17 Myeloproliferative DDs (Poorly Differentiated Neoplasms)  Antipsychotic 16.5% 15.3% 17.5% <0.0001 MDC16 Blood and Blood Forming Organs and Immunological Disorders  Iatrogenic alerts (%) * Long half-life benzodiazepine 9.7% 8.8% 10.3% <0.0001 MDC14 Pregnancy, Childbirth And Puerperium MDC15 New-born And Other Neonates (Perinatal Period of hospitalization avoided had no IA occurrence.	AR 3% 12% 9% 3% 4%
	Digoxin MDC24	4.0 % Multiple Significant Trauma 3.5%		4.4%	<0.0001
	Polypharmacy (%)* MDC25	89.5 % Human Immunodeficiency Virus Infection 88.4%	90.3%	<0.0001
	MDC26	Severe multiple trauma
	MDC27	Organ transplants
	MDC28	Sessions
	MDC90	Errors and other unclassifiable stays
	MDC in italic were not present in our database

* Percentage per 6-month periods NSAID: Nonsteroidal anti-inflammatory drug

FUNDING:

This study received help from FRM (Fondation pour la Recherche Médicale: http://www.frm.org/) and from "Fondation France Alzheimer", http://www.francealzheimer.org/recherche-scientifique. The funding source was not involved in the writing of the article or the decision to submit it for publication.

AKNOWLEDGMENT:

We thank Benoit Lavallart who's working at the Ministry of Health, and Dr.Carole Micheneau who's working at the French National Authority for Health for their assistance in the development of the project.

DISCUSSION

The Iatrogenic Alerts (IAs) represent a restricted selection of explicit criteria developed by French health professionals [START_REF]Prescription Médicamenteuse chez le Sujet Agé (PMSA) -Programme Pilote 2006-2013[END_REF] from the existing sets [START_REF] Laroche | Potentially inappropriate medications in the elderly: a French consensus panel list[END_REF][START_REF] Spinewine | Appropriate prescribing in elderly people: how well can it be measured and optimised[END_REF][START_REF] Gallagher | Screening Tool of Older Person's Prescriptions) and START (Screening Tool to Alert doctors to Right Treatment). Consensus validation[END_REF][START_REF]The American Geriatrics Society 2012 Beers Criteria Update Expert Panel. American Geriatrics Society updated Beers Criteria for potentially inappropriate medication use in older Adults[END_REF][START_REF] Price | Association between potentially inappropriate medications from the Beers Criteria and the risk of unplanned hospitalization in elderly patients[END_REF][START_REF] Price | Impact of specific Beers Criteria medications on associations between drug exposure and unplanned hospitalisation in elderly patients taking high-risk drugs: A case-time-control study in Western Australia[END_REF] to assess the appropriateness of prescription in elderly people.

To our knowledge, this is the first study to analyze the potential association between these IAs and hospitalizations in a selected population known to be at risk for repeated admissions (the elderly people treated for dementia). We found that IAs were closely linked to hospitalization, since 22% of all hospitalizations (whatever the leading cause) in this population were associated with cardiovascular and/or psychotropic IAs. In our secondary more accurate analysis, we calculated that 17% of "potentially ADE-related" hospitalizations were associated with psychotropic IAs and 4% with cardiovascular IAs. This estimate is in agreement with previous assessments that 5-20% of hospital admissions could be related to drug side effects [START_REF] Beijer | Hospitalisations caused by adverse drug reactions (ADR): a meta-analysis of observational studies[END_REF][START_REF] Gurwitz | Incidence and preventability of adverse drug events among older persons in the ambulatory setting[END_REF].

As expected, IAs were generally common with 40% of the population experiencing at least one six-month period with an IA. But, a surprising finding was that an IA was present for 2 years (at all times) for 15% of the patients. This clearly shows the lack of information of practitioners regarding the absence of benefice of some psychotropic and cardiovascular drugs combinations given the potential risks and possibility of alternative treatment.

The population under study showed typical characteristics of elderly populations regarding prescriptions and hospitalizations. The incidence of polypharmacy was significant, as was the case with previous reports [START_REF] Budnitz | Emergency hospitalizations for adverse drug events in older Americans[END_REF][START_REF] Gurwitz | Incidence and preventability of adverse drug events among older persons in the ambulatory setting[END_REF][START_REF] Wallace | Appropriate prescribing and important drug interactions in older adults[END_REF][START_REF] Geriatrics | Expert Panel on the Care of Older Adults with Multimorbidity. Guiding principles for the care of older adults with multimorbidity: an approach for clinicians[END_REF]. The risk of hospitalization was typical of old age [START_REF] Budnitz | Emergency hospitalizations for adverse drug events in older Americans[END_REF][START_REF] Voisin | Descriptive analysis of hospitalizations of patients with Alzheimer's disease: a two-year prospective study of 686 patients from the REAL.FR study[END_REF], and it increased in the case of morbidity, polypharmacy, prescription of anticoagulant, antidiabetic and digoxin, as previously described [START_REF] Budnitz | Emergency hospitalizations for adverse drug events in older Americans[END_REF][START_REF] Beijer | Hospitalisations caused by adverse drug reactions (ADR): a meta-analysis of observational studies[END_REF][START_REF] Gurwitz | Incidence and preventability of adverse drug events among older persons in the ambulatory setting[END_REF][START_REF] Budnitz | National surveillance of emergency department visits for outpatient adverse drug events[END_REF][START_REF] Wallace | Appropriate prescribing and important drug interactions in older adults[END_REF][START_REF] Geriatrics | Expert Panel on the Care of Older Adults with Multimorbidity. Guiding principles for the care of older adults with multimorbidity: an approach for clinicians[END_REF][START_REF] Saedder | Number of drugs most frequently found to be independent risk factor for serious adverse reactions: a systematic literature review[END_REF][START_REF] O'dwyer | Factors associated with polypharmacy and excessive polypharmacy in older people with intellectual disability differ from the general population: a cross-sectional observational nationwide study[END_REF]. These associations between hospitalizations and drugs known to be the highest purveyors of ADE (anticoagulant /


MD Adrien Lemaignen
email: adrien.lemaignen@univ-tours.fr

Louis Bernard

Simon Marmor

Tristan Ferry

Leslie Grammatico-Guillon

Pascal Astagneau

Epidemiology of complex bone and joint infections in France using a national registry: the CRIOAc network

Keywords: 3 -Tables: 2 -Supplemental files: 5 Bone and joint infections, epidemiology, France, prosthetic joint infection

Introduction

Bone and joint infections (BJI), including septic arthritis and osteomyelitis are becoming of immediate concern because of a significant human and economic burden [START_REF] Laurent | Key features of bone and joint infections following the implementation of reference centers in France[END_REF][START_REF] Kehrer | Increasing incidence of pyogenic spondylodiscitis: a 14-year population-based study[END_REF][START_REF] Kremers | Trends in the epidemiology of osteomyelitis: a population-based study, 1969 to 2009[END_REF][START_REF] Lenguerrand | Revision for prosthetic joint infection following hip arthroplasty: Evidence from the National Joint Registry[END_REF][START_REF] Malizos | Global Forum: The Burden of Bone and Joint Infections: A Growing Demand for More Resources[END_REF]. The incidence is estimated to be 70/100,000 patients-year in France, and increases with age [START_REF] Laurent | Key features of bone and joint infections following the implementation of reference centers in France[END_REF]. Population ageing with a higher prevalence of comorbidities, and increasing arthroplasty procedures could explain partly this trend [START_REF] Nemes | Historical view and future demand for knee arthroplasty in Sweden[END_REF]. In parallel, microbiological characteristics as well as clinical management of BJI are evolving for the last decade [START_REF] Benito | Time trends in the aetiology of prosthetic joint infections: a multicentre cohort study[END_REF][START_REF] Marang-Van De Mheen | Variation in Prosthetic Joint Infection and treatment strategies during 4.5 years of follow-up after primary joint arthroplasty using administrative data of 41397 patients across Australian, European and United States hospitals[END_REF]. BJI represent a very heterogenous group of pathology leading to complex medical cares.

Device-associated infections, first-line management failure, sometimes due to multidrug resistant or difficult-to-treat micro-organisms, and multiple comorbidities are associated with higher morbidity and costs and require multi-professional competencies [START_REF] Grammatico-Guillon | Bone and joint infections in hospitalized patients in France, 2008: clinical and economic outcomes[END_REF][START_REF] Bauer | Impact of a multidisciplinary staff meeting on the quality of antibiotherapy prescription for bone and joint infections in orthopedic surgery[END_REF]. To face the problem, the French Ministry of Health has created 30 several reference centers located in university hospitals since 2008, so called Centres de référence des infections ostéoarticulaires complexes (CRIOAc) [START_REF] Ferry | The CRIOAc healthcare network in France: A nationwide Health Ministry program to improve the management of bone and joint infection[END_REF]. These centers are responsible for the organization of multi-professional expertise on the management of BJI in their geographic unit, especially for complex BJIs (cBJI, defined below). This is made through periodic multidisciplinary meeting (MM) hold in the reference center.

A registry for BJI was then set up in 2012 to perform the MM and to collect individual data for patients referred to each reference center, as the decision taken during MM [START_REF] Lemaignen | Computerized registry as a potential tool for surveillance and management of complex bone and joint infections in France[END_REF]. The main objective of this study was to describe the main characteristics and advised management for patients referred to cBJI reference centers in France between 2014 and 2019, and to determine significant temporal trends.

Methods

Study design

This multicentric observational study was a descriptive analysis of the data from the French registry of reference centers for cBJI management.

Patients

All consecutive adult patients presented in MM for a suspected or confirmed BJI and recorded in the registry from January 2014 to December 2019 were included in this study. Data-quality could not be analyzed for 7 centers, therefore patients from these reference centers were not included in the analysis.

Study variables

The definition of complex BJI (cBJI) was based on the presence of at least one of the following criteria determined during a MM: Host criteria (severe comorbidity limiting treatment options, severe drug allergy or intolerance); Microbiological criteria (difficult-totreat micro-organism(s) with or without multidrug resistance); Surgical criteria (BJI requiring large bone resection and bone and/or soft-tissue reconstruction); Relapse or failure of a previous episode of BJI. The classification as cBJI during MM was under the responsibility of each reference center.

Variables recorded in the registry were previously detailed [START_REF] Lemaignen | Computerized registry as a potential tool for surveillance and management of complex bone and joint infections in France[END_REF]. They include: i/ characteristics of the MM (date, localization); ii/ demographics (age, sex) and comorbidities;

iii/ clinical and biological data; iv/ characteristics of the infection (localization, rank of infection, device presence or not, microbiological identification and resistance to antibiotics); and v/ decision of MM: recommended surgery, proposed antibiotic treatment, definition as a complex BJI or not and criterion for complexity.

The registry does not contain outcome data, but some patients are presented several times in MM. We considered several MM as a same infectious episode when the delay between 2 presentations in MM was less than one year in the absence of device, and less than two years when patients presented device-associated infection. These time intervals are usually retained in the literature for definition of BJI cure [START_REF] Zimmerli | Orthopaedic biofilm infections[END_REF][START_REF] Li | Oral versus intravenous antibiotic treatment for bone and joint infections (OVIVA): study protocol for a randomised controlled trial[END_REF].

Episodes have been classified into 7 different mutually exclusive types, according to the main mechanism of infection: 1/prosthetic joint infections (PJI); 2/osteomyelitis: osteomyelitis with or without contiguous septic arthritis; 3/native arthritis: isolated septic arthritis, without foreign device; 4/septic pseudarthrosis: delayed healing of a fracture-related infection, with or without associated foreign device; 5/vertebral infections; 6/other/undefined: affections involving external fixators, soft tissues (muscle, tendons, skin, abscesses etc.), tumoral processes or other mechanisms not mentioned above ; 6/multiple: several associated mechanisms among the previous ones and several sites of infection.

Analysis

We considered for analysis aggregated data from individual infectious episodes for patient's characteristics, BJI characteristics and MM decision (one patient could be presented for several different infectious episodes). Descriptive statistics included frequency analyses (percentages) for categorical variables and mean (standard deviation [SD]) or median (25 th and 75 th quantile [Q25-Q75]) for quantitative variables. When necessary, comparisons were made using chi-square test, or student t-test as needed. Linear regression analysis and a nonparametric Mann-Kendall test were used to assess a temporal trend. Significance was assumed for a p-value < 0.05. Missing data were presented in the different tables and figures.

Statistical analyses were performed using the R statistical package version 3.6.3 (The R Foundation for Statistical Computing, https://www.R-project.org/).

Ethics

The registry was endorsed by the French National Data Protection Agency in 2012 (CNIL / 2012-220). Non-opposition to the use of the recorded data for research purposes is systematically sought for each patient included in the cohort. Funding of this registry and the reference centers is supported by the French Ministry of Health.

Results

Registry population

From 2014 to 2019, 37,289 patients were recorded in the French registry for cBJI. Data were analyzed for patients from the 23 centers included in this study, representing 27,483 individual patients, corresponding to 28,365 distinct infectious episodes requiring 47,262 presentations in MM (mean number of MM by infectious episode: 1.66 [SD=1.37], max=30).

In excluded centers, type of infections, microbiological data, surgical and medical management were comparable to those in included centers, but with a significantly higher amount of missing data, indicating a lower reliability of data. The majority of the BJI presented concerned prosthetic joint infections (PJI), and 16,370 infectious episodes (57.7%) involved foreign device infection (Figure 1). The number of infectious episodes presented each year increased over the study period from 3,711 in 2014 to 6,047 in 2019 (Supplemental files, Appendix 1). About two-third of the cases were cBJI (Table 1). Considering the type of the BJI classified as complex, multiple infections (445/537: 82.9%) and septic pseudarthrosis (1,039/1,454: 71.5%) had the highest rate of complexity (Figure 1). A comorbid condition was the most prevalent criteria of complexity (9,365 infectious episodes) and BJI were considered as complex with a mean of 1.54 (SD=0.76) criteria of complexity (9,466 infectious episodes with 2 or more criteria). These rates remained stable over years, without significant trend among different criteria.

A microbiological documentation was recorded for 19,574 infectious episodes (69.0%).

Microbiology was detailed by type of infection in Figure 2 2). For the others, several reasons may have conducted to the absence of antimicrobial therapy: 1/advice for cessation (end of treatment, post-second stage of a two-stage exchange, amputation, creation of effective drain fistulae); and 2/ to a lower extent absence of confirmed infection. Among the detailed antibiotic treatment proposals (22,482 infectious episodes), a combination was advised in 19,152 infectious episodes (85.2%). During one infectious episode, patients could have been presented several times in MM with different antibiotic therapies proposed (i.e. for microbiologic adaptation, previous failure etc.). At the MM level, Beta-lactams were the most widely used class of antibiotics with 26,200 prescriptions out of the 39,271 MM with a proposed antibiotic therapy (66.7%). Antibiotics most used were broad spectrum beta-lactams (piperacilline/tazobactam and cefepime, accounting for 17% and 10% of total number of MM, respectively), then amoxicillin (7.7%), ceftriaxone (5.8%), cefazolin (5.3%), amoxicillin/clavulanate (4.2%) and cloxacillin (3.1%). Other main classes were quinolones (12,498 MM), glycopeptides (9,867 MM) and rifampicin (9,269 MM) (Supplemental files, Appendix 4). The class of antibiotics used according to the main micro-organisms was detailed in Supplemental files, Appendix 5. Notably, fluoroquinolones-rifampicin combination was advised after 5,827 MM, including 3,131 infections due to staphylococci, and 1,786 polymicrobial infections.

Prosthetic joint infections

In total, including multiple sites infections and vertebral prosthesis, 12,125 episodes of PJI were presented, and involved mainly hip (6,458 episodes) and knee (4,840 episodes) (Figure 1). Considering individually every hip or knee PJI, infections were considered as complex in 4,310 (66.7%) and 3,357 episodes (69.3%), due to previous management failure in 2,065 (32.0%) and 1,833 episodes (37.9%), and/or to complex surgery in 1,719 (26.6%), and 1,572 episodes (32.5%), respectively. The acute, chronic or hematogenous character of infection was not recorded in the database. Microbiological documentation was notified in 4,532 hip PJIs (70.2%) and 3,326 knee PJIs (68.7%) episodes with predominance of Staphylococcus aureus (1,698 and 1,276), Coagulase negative staphylococci (1,491 and 1,175) and polymicrobial infections (1,024 and 679). Microbiology was similar between both localizations except for Enterobacteriaceae (853; 13.2% vs 511; 10.6%, p<0.001), anaerobic bacteria (435; 6.7% vs 228; 4.7%, p<0.001), and streptococci (542; 8.4% vs 531; 11.0%, p<0.001). Trends remained stable over time (Figure 3). Medical management was similar between hip or knee PJIs and depended of microbiological findings. During the study period, we noticed a significant rise both in single antibiotic therapies and multiple combinations of antibiotics (3 antibiotics or more), associated with a significant decrease of non-documented treatment (Figure 3). Rifampicin was used in 30.1% of episodes, in association with quinolones in 18.2%. A long-term suppressive antibiotic treatment was advised in 4.6% of episodes, after an initial "standard" 6-to-12 weeks therapy. It was prescribed as a palliative treatment, usually for at least 6 months and often for life, as a single molecule. The main antibiotics advised were cyclins (doxycycline and minocyclin). Other antibiotics used were cotrimoxazole, amoxicillin, pristinamycine, clindamycin, depending on the susceptibility of micro-organisms. Considering surgical management, DAIR (debridement, antibiotics and implant retention) was proposed for 1,671 (25.9%) and 1,275 (26.3%) episodes, whereas onestage exchange for 1,979 (30.6%) and 1,383 (28.6%) episodes, and two-stage exchange for 860 (13.3%) and 737 (15.2%) episodes. There was no significant trend for these procedures during the study period (Figure 3). Coverture procedure, arthrodesis, or amputation were proposed mainly for knee PJI (239 vs 20; 174 vs 10; 132 vs 22, respectively, p<0.001), whereas joint resection was mainly advised for hip PJI (117 vs 22, p<0.001). In total, 1.271 patients (11.6%) had several procedures. Among them, when DAIR was the first option (256), one-or two-stage revisions were performed in 151 (59.0%) and 122 patients (47.7%), respectively (both for 17 patients).

Discussion

Main results

The CRIOAc network has been set up to provide access to the best care using the specialized multidisciplinary experience of chosen centers for patients presenting with complex BJI across the country [START_REF] Laurent | Key features of bone and joint infections following the implementation of reference centers in France[END_REF][START_REF] Ferry | The CRIOAc healthcare network in France: A nationwide Health Ministry program to improve the management of bone and joint infection[END_REF]. If the definition of complexity is not widely recognized, it corresponds with higher health costs and complications [START_REF] Laurent | Key features of bone and joint infections following the implementation of reference centers in France[END_REF]. Due to comorbidities, difficult-totreat micro-organisms, previous failure or complex surgical management, the recognition of a complex BJI should lead to refer the patient to a specialized multidisciplinary team in order to optimize his care. A detailed description of these infections may permit to improve their surveillance and management.

The nationwide registry from this network recorded a large amount of data for various types of BJI with a mean of 5,726 new infectious episodes each year (SD=870) from 2014 to 2019.

Most of them were qualified as complex, due to comorbid conditions, previous treatment failure, need for complex surgical procedures or due to resistant or atypical microorganisms. This definition of complexity has previously shown to be poorly reproducible outside of a multidisciplinary approach [START_REF] Laurent | Multidisciplinary team meeting for complex bone and joint infections diagnosis: The PHICTOS study[END_REF]. A scoring-tool deducted from this registry could be useful to improve the homogeneity of the definition for cBJI. This cohort was not designed as a surveillance tool for BJI and was mainly dedicated to most complex situations, not permitting an exhaustive record of BJI. However, with 41% of all infectious episodes presented in reference center (14, 16), mostly performed for osteoarthritis (17,[START_REF] Courtney | Arthroplasty Registries: Improving Clinical and Economic Outcomes[END_REF]. With an estimated PJI incidence of 2.3% person-year [START_REF] Grammatico-Guillon | Surgical Site Infection After Primary Hip and Knee Arthroplasty: A Cohort Study Using a Hospital Database[END_REF], one could expect about 6,000 episodes each year.

There is no other longitudinal cohort dedicated to BJI nor PJI in France. Thus, as a prospective multicenter cohort with more than 5,000 new infectious episodes each year, this registry is a unique opportunity to monitor trends in epidemiology and management of BJI and PJI in France. For example, monitoring temporal trends in the rate of complexity for previous failures could be a useful tool to monitor the overall effectiveness of the CRIOAc network in its assignment of training and local networking. Indeed, although it remained stable from 2014 to 2019, a relative decrease of these complex infections for failure could signify a better overall management of primary BJIs.

If the French Society of Orthopedics set up a national cohort of total hip arthroplasties in 2007, this registry does not detail characteristics and management of PJIs [START_REF] Delaunay | What are the causes for failures of primary hip arthroplasties in France?[END_REF]. Another source of information resides in large population-based epidemiological studies with data extracted from medical information systems [START_REF] Laurent | Key features of bone and joint infections following the implementation of reference centers in France[END_REF][START_REF] Grammatico-Guillon | Surgical Site Infection After Primary Hip and Knee Arthroplasty: A Cohort Study Using a Hospital Database[END_REF]. These studies have a high potential for exhaustivity and permit a good estimation of BJI incidence. For this purpose, they have recently been chosen for semi-automated routine surveillance of hip and knee PJI in France [START_REF] Meur | Health insurance database for post-discharge surveillance of surgical site infection following arthroplasty[END_REF]. However, some comorbidities, microbiology and detailed management are not well encoded in hospital discharge databases and may not be monitored by this tool [START_REF] Grammatico-Guillon | Surgical Site Infection After Primary Hip and Knee Arthroplasty: A Cohort Study Using a Hospital Database[END_REF][START_REF] Grammatico-Guillon | Quality assessment of hospital discharge database for routine surveillance of hip and knee arthroplasty-related infections[END_REF]. Thus, the French registry of CRIOACs could complete this surveillance tool providing more detailed data, particularly for most complex cases. Furthermore, the registry provides information on other rare BJIs which are poorly studied elsewhere (septic pseudarthrosis, chronic osteomyelitis, vertebral infections). Due to its size, this cohort can also detect infections due to atypical or rare microorganisms and permits to investigate them more precisely by returning to patient records. This study has some limitations. As previously described [START_REF] Lemaignen | Computerized registry as a potential tool for surveillance and management of complex bone and joint infections in France[END_REF], the registry was not originally designed for epidemiological studies but as an activity audit tool, with consequent heterogeneity in data-filling. However, data-quality analysis showed acceptable parameters. Furthermore, comparison with other cohorts from the literature showed consistent results indicating acceptable reliability. Indeed, considering PJI, comorbidities [START_REF] Manning | Clinical Characteristics, Etiology, and Initial Management Strategy of Newly Diagnosed Periprosthetic Joint Infection: A Multicenter, Prospective Observational Cohort Study of 783 Patients[END_REF][START_REF] Kapadia | Periprosthetic joint infection[END_REF] and microbiology [START_REF] Benito | Time trends in the aetiology of prosthetic joint infections: a multicentre cohort study[END_REF][START_REF] Aggarwal | Organism profile in periprosthetic joint infection: pathogens differ at two arthroplasty infection referral centers in Europe and in the United States[END_REF] were comparable to other international cohorts. In our registry hip infections accounted for 53% and knee for 39% of the PJIs, in the opposite direction to some other studies. This is mainly due to the predominance in France of hip arthroplasties compared to knee arthroplasties in a ratio of 2 to 1 [START_REF] Grammatico-Guillon | Surgical Site Infection After Primary Hip and Knee Arthroplasty: A Cohort Study Using a Hospital Database[END_REF]. As this registry captures approximately 40% of all prosthetic joint infections, it appears to be a good proxy of national epidemiology. As previously reported [START_REF] Lemaignen | Computerized registry as a potential tool for surveillance and management of complex bone and joint infections in France[END_REF], categorical data for comorbid conditions did not contain missing data because of the type of data-entry in the e-CRF: only positive data were filled without distinction between negative or missing data: considering it as negative offered better consistency of data than considering it as missing. Conversely, continuous variables like precise height and weight, CRP, and creatinine level were not retained for analysis due to a too high amount of missing data. Unfortunately, in addition to missing data in some variables of interest, some information is lacking in the MM report form (i.e: timing of infection, primary arthroplasty indication, precise antimicrobial susceptibilities of microorganisms). However, this information is often detailed in unstructured data and natural language processing could help extracting informative data. In parallel, better homogenizing data filling between centers and monitoring of data quality will facilitate data analysis. A good example is for the methicillin susceptibility of SA: we preferred the notion of "SA with resistance" over "methicillin-resistant SA", because some centers classified as "with resistance" some methicillin-susceptible SA with resistance to oral treatment as quinolones and/or rifampicin. Thus, most of "SA with resistance" are MRSA, but we cannot precise their exact number. Finally, the lack of systematic follow-up data record prevents tracking of longterm outcome, and only the patients with management failure will be seen again in MM. This introduces recruitment and survival bias which impede proper analysis of outcomes.

Currently, a return to patient files is necessary to record these outcome data. The registry facilitates the identification of patients of interest for such retrospective research. But the implementation of systematic follow-up in selected voluntary reference centers could partially resolve this problem in the future.

Conclusion

The French model of structured reference centers for complex BJIs allows optimization of care for BJIs with multidisciplinary management. Introducing the concept of complex BJIs allows to focus on those infections responsible for the most of complications and highest health-costs. The clinical data recorded from these reference centers feed the national registry of CRIOACs, a unique opportunity to draw up a detailed picture of the epidemiology of BJIs in France and to follow on a large scale the trends of these infrequent infections.

  085 individual episodes from 2014 to 2019 considering the entire database, a mean of 2,711 infectious episodes/year, and 3,716 episodes in 2019), PJI from the registry represented a large proportion of estimated PJI in France during the study period. Indeed, total hip arthroplasties increased from 128,564 in 2009 to 153,128 in 2019 and total knee arthroplasties increased from 71,476 in 2009 to 115,591 in 2019 (

Figure 1 :Figure 2 : 2 :

 122 Figure 1: Flow chart of infectious episodes by type of infection * 80 patients were seen in several reference centers; ** refers to multiple mechanisms and multiple sites; PJI: Prosthetic joint infections; LLE: lower limb extremity, i.e. foot and ankle; SSTI: Skin and soft tissue infection; BJI: bone and joint infections

Figure 3 :

 3 Figure 3: Main trends in the management of prosthetic joint infections from 2014 to 2019Scatterplots of monthly percentages of episodes presenting with the selected variables among prosthetic joint infection episodes. Solid lines correspond to the fitted trend regression analysis; ß: coefficients of the regression analysis; P: p-value of the corresponding Mann-Kendall test, p<0.05 are considered as significant. A: Microbiological documentation: Percentage of episodes due to Staphylococcus aureus, to polymicrobial infections and to resistant micro-organisms. B: Medical treatment advised for each episode: Single therapy, multiple combination therapy (3 antibiotics or more) and unspecified treatments. C: Surgical procedures advised: Debridement and antibiotic with implant retention (DAIR), onestage revision and two-stage revision.

  and in Supplemental files, Appendix 2. Microbiology remained stable over time. Staphylococcus aureus was the main pathogen in all types of BJI with 8,596 infectious episodes (45.1% of documented episodes). Polymicrobial infection was reported for 6,140 infectious episodes (32.2%), and was often associated with multiple infections (216/537, 40.2%) or osteomyelitis (2,508/8,384, 29.9%).

	When polymicrobial, mean number of different species was 2.73 (SD:1.10) ranging from 2 to
	15. Resistant microorganisms were involved in 3,977 documented infectious episodes
	(20.9%), and were significantly associated with foreign device (22.1% vs 17,8%, p<0.001)
	and multiple infections (37.2% vs 19.9%, p<0.001). Their prevalence remained stable over
	time.
	Detailed advised surgical procedures are resumed in Appendix 3 (Supplemental files).
	Surgical procedures were advised for 23,768 infectious episodes (83.8%), mainly cleaning
	and device removal surgery (9,678/23,768 and 9,818/23,768, respectively). An antibiotic
	treatment was proposed for 23,984 infectious episodes (84.6%) (Table

Acknowledgements and affiliations:

We especially thank Dr Thibault Dhalluin for his help in the methodological design. We also thank all the members of the CRIOAC network, the medical staff (orthopedist surgeons, infectious disease specialists, microbiologists and the others) and paramedical staff, who care for the patients presented during the multidisciplinary meetings.

Funding statement: None of the authors received any industrial grant regarding the current study. The CRIOAC network and the French Registry for cBJI are funded by the Direction Générale de l'Offre de Soin (DGOS) / French Ministry of Health. No author has conflict related to the current study. Members of the Scientific Committee of the CRIOAc network: Pr. Tristan Ferry (Président, Hospices Civils de Lyon, Service de Maladies Infectieuses et Tropicales, Lyon, France), Dr. Simon Marmor (Groupe Hospitalier Diaconesses-Croix Saint Simon, Service d'orthopédie, Paris, France), Pr. Didier Mainard (CHU de Nancy, Service d'Orthopédie, Vandoeuvre-lès-Nancy, France), Pr. Eric Stindel (CHU de Brest, Service d'orthopédie, Brest, France), Pr. Éric

Author's contributions: AL, LB, PA, LGG, SM, TF and the Scientific Committee for Complex Bone and Joint Infections Reference Centers conceived the study protocol. AL, LB, SM, TF, and members of the CRIOAc network included patients in the registry. AL and LGG ensured the statistical analysis. AL, LGG, PA and LB wrote the manuscript. All authors reviewed the final manuscript and proposed significant modifications.


Lee S Nguyen

Marie Bretagne

Jennifer Arrondeau

Noel Zahr

Stephane Ederhy

Baptiste Abbar

Bruno Pinna

Yves Allenbach

Jean-Paul Mira

Javid Moslehi

Michelle Rosenzwajg

Joe-Elie Salem
email: joe-elie.salem@aphp.fr

Orcid Ids Lee

S Nguyen

Reversal of immune-checkpoint inhibitor fulminant myocarditis using personalized-dose-adjusted abatacept and ruxolitinib: proof of concept

BACKGROUND

Immune-checkpoint inhibitors (ICIs) are indicated for a growing number of cancer types. [START_REF] Geraud | Clinical pharmacology and interplay of immune checkpoint agents: a yin-yang balance[END_REF] ICIs are antibodies targeting the programmed cell-death-protein-1 (PD1), its ligand (PDL1), or cytotoxic-T-lymphocyteassociated-protein-4 (CTLA4) and restore T-cell cytotoxicity against cancer cells. 1 However, ICI therapies may be hampered by fulminant myocarditis, which is often fatal and results from T-cells and macrophages infiltration into the myocardium. [START_REF] Salem | Cardiovascular toxicities associated with immune checkpoint inhibitors: an observational, retrospective, pharmacovigilance study[END_REF] Salem et al have recently shown that abatacept, a CTLA4 immunoglobulin fusion protein, is a promising treatment strategy for life-threatening glucocorticoid-refractory ICI-myocarditis in a case report. 3 4 These findings were supported using a genetic mouse model which recapitulates clinical and pathological features of ICI-myocarditis. [START_REF] Wei | A genetic mouse model recapitulates immune checkpoint inhibitor-associated myocarditis and supports a mechanism-based therapeutic intervention[END_REF] In this model, CTLA4 and PD1 functionally interact for myocarditis development and intervention with CTLA4-Ig (abatacept) attenuates myocarditis. [START_REF] Wei | A genetic mouse model recapitulates immune checkpoint inhibitor-associated myocarditis and supports a mechanism-based therapeutic intervention[END_REF] However, optimal abatacept dosing scheme and combination with other synergistic immunosuppressants for glucocorticoid-refractory ICI-myocarditis is unknown. By binding CD80/CD86, CTLA4 agonists (abatacept, belatacept) act on antigen-presenting-cells (eg, macrophages) and lead to global T-cell anergy with limited off-target effects and reverse pathways activated by ICI. 1 4 In their approved indications (rheumatic arthritis for abatacept, kidney graft rejection prophylaxis for belatacept), the circulating monocytes CD86 receptor occupancy (CD86RO, ie, CTLA4 agonists receptors), is a relevant pharmacodynamic biomarker of their clinical activity, with CD86RO ≥80% as a target for full efficacy. 5 6 However, such measurements have not been made with abatacept during use for ICI-myocarditis.

Here, we detail the management of a patient with thymoma treated by pembrolizumab (anti-PD1) who developed fulminant corticosteroid and mycophenolate mofetilresistant myocarditis requiring circulatory mechanical support. This event was reversed using high-dose abatacept guided by CD86RO immune-monitoring and abatacept circulating levels. Additionally, ruxolitinib, a JAK (Janus-Kinase) inhibitor which impairs T-cell Open access activation via blockade of pro-inflammatory cytokines and is used to treat graft vs host disease (a condition in which donor T-cells attack host tissue), was also administrated, [START_REF] Zeiser | Ruxolitinib for Glucocorticoid-Refractory acute graft-versus-host disease[END_REF] given its expected rapid synergistic effect with abatacept (acting downstream in the immunological synapse) and the severity of initial presentation. [START_REF] Geraud | Clinical pharmacology and interplay of immune checkpoint agents: a yin-yang balance[END_REF] METHODS FOR IMMUNE MONITORING Blood samples were collected in EDTA tubes. Monocytes and T-lymphocytes were analyzed by flow cytometry using monoclonal antibodies(mAb) as previously described 8 : CD45-PacificBlue, CD14-APC Alexafluor700, CD86-Phycoerythrin, or an isotype control-Phycoerythrin (all Beckman-Coulter) and CD279(PD1)-BrilliantViolet510(Biolegend). Monocytes were identified as CD45 + CD14 + cells, CD86 mean fluorescent intensity (MFI) was analyzed on gated monocytes and compared with labeling with an isotypic control (online supplemental figure 1). CD86RO was calculated as follows: (1) MFI s -MFI ns =ΔMFI, where MFI s is MFI of the Phycoerythrinlabeled anti-CD86 mAb; MFI ns is the non-specific MFI with an isotype control; ΔMFI is the difference between these two values, representing a relative measurement of specific binding and (2) CD86RO at each timepoint was calculated using: [1-(ΔMFI timepoint / ΔMFI baseline )] where ΔMFI baseline is calculated from a sample extracted within 1 hour of first abatacept dose (online supplemental figure 1). 5 6 For PD1 expression, the gating strategy is described in online supplemental figure 2; CD3 + T-lymphocytes were gated in lymphocytes, followed by CD4 + and CD8 + T-cells gating within CD3 + T-cells. The % of PD1 + cells were then analyzed in each population. [START_REF] Pitoiset | Deep phenotyping of immune cell populations by optimized and standardized flow cytometry analyses[END_REF] Methods for assessment of abatacept and pembrolizumab circulating levels are in online supplemental data.

CASE-REPORT

A 25-year-old man was admitted to the intensive care unit (ICU) with fulminant ICI-myocarditis. Six months earlier, he was diagnosed with non-operable thymoma extending to lung and pleura (figure 1). First-line chemotherapy included cyclophosphamide, doxorubicin, and cisplatin, with partial response; but still unsuitable for surgical removal. Thymoma-cells expressed high levels of PDL1, prompting pembrolizumab treatment after expert panel consultation. Baseline troponin levels were normal and echocardiography showed normal left ventricular ejection fraction (LVEF:65%).

Two weeks after pembrolizumab initiation, the patient presented with chest pain, subtle myalgia and was admitted to cardiology (index event, day 0 (D0)). Coronary angiography was normal with cardiac MRI showing decreased LVEF, mild pericardial effusion, edema on T2-mapping affecting LV inferior wall and junctional late gadolinium enhancement; and LV endomyocardial biopsy identifying a pathological inflammatory infiltrate mainly composed of CD3 + T-cells (20/mm²) and CD68 + macrophages (7 / mm²) compatible with ICI-myocarditis. Muscular biopsy confirmed the concurrent ICI-myositis with dense focal inflammatory infiltrates also mainly composed of T-cells and macrophages with necrotic myofibers on pathology. Troponin-T and creatine-kinase rose, respectively, to 3000 ng/L (upper-limit-normal-value:14 ng/L) and 3714 IU/L (upper-limit-normal-value <190 IU/L), while LVEF deteriorated to <10%, despite prompt administration of intravenous boluses of methylprednisolone(1 g/ day)×3 doses and addition of mycophenolate-mofetil (figure 2). He was transferred to ICU on day 8, with cardiogenic shock, persistent ventricular tachycardia, and severe intraventricular conduction blockade, requiring implantations of an extracorporeal life support (ECLS) (figure 2).

Baseline level of CD86 expression on circulating monocytes were evaluated to allow for subsequent immunemonitoring on abatacept to reach CD86RO≥80% (figure 2). 5 6 This threshold has been demonstrated to be Open access relevant in current indications of CTLA4 fusion proteins, particularly belatacept. 1 5 6 This strategy resulted in a loading dose of intravenous abatacept 20 mg/kg (similar to belatacept loading dose equivalent given in graft rejection prophylaxis), [START_REF] Geraud | Clinical pharmacology and interplay of immune checkpoint agents: a yin-yang balance[END_REF] in combination with oral ruxolitinib 15 mg two times daily and intravenous methylprednisolone 2 mg/kg starting on day 8. Within a week, ventricular arrhythmias resolved, LVEF recovered to 35%-40%, and troponin progressively decreased to ~1000 ng/L. CD86RO increased near 80% after each abatacept injection, but monitoring showed initially (the first three doses) very fast consumption of abatacept with maximal abatacept plasma concentration dropping from ~300 to ~150 µg/ mL (50% clearance) consistent with maximal CD86RO decreasing from ~80% to below 40% in ~2-3 days vs a known half-life of ~13 days 1 (figure 2). All decisions regarding timing and dosage of abatacept injections were made on CD86RO assessment, clinical (including ECG with ventricular patterns, online supplemental figure 3), LVEF and biological evolution (troponin-T). Patient was successfully weaned from inotropes within 48 hours and from ECLS within 7 days after abatacept/ruxolitinib start. After ECLS weaning, the only significant recurrences in sustained ventricular arrhythmia occurred on day 17 and was concomitant with a negative CD86RO, prompting an additional abatacept dosing. Corticosteroids and ruxolitinib were progressively stopped over a month. The patient ultimately required 5 injections of abatacept 20 mg/kg (day 8, day 11, day 18, day 25, and day 32).

On day 40, the patient fully recovered clinically, with LVEF restoring to 60%. A wearable defibrillator showed no significant arrhythmic events to day 106. Ramipril and beta blockers were started on day 18-day 20 and were maintained after discharge. Pembrolizumab was permanently discontinued. Further CT-scan assessment showed tumor shrinkage compatible with a surgical procedure; however, the patient refused surgery. 4 months after pembrolizumab dosing, the tumor relapsed, concomitant to restoration of lymphocytes expressing PD1 (15% vs. <1% just after pembrolizumab), correlating with pembrolizumab circulating levels being undetectable (figure 1). The patient was then treated with combination of carboplatin and paclitaxel.

DISCUSSION

This case shows the potential of reversal of a fulminant ICI-myocarditis using receptor occupancy guided and tailored dosing of abatacept, combined with ruxolitinib and corticosteroids. Abatacept (a CTLA4 fusion-protein), Open access antagonizes the activation of ICI pathways by inhibiting the upstream antigen-presenting-cells (monocytes); meanwhile, the association with corticosteroids and ruxolitinib, a JAK inhibitor, inhibits T-cell signals either directly (corticosteroids), or indirectly through cytokine pathways inhibition (ruxolitinib). 1 9 As T-cells and macrophages are critical in the development of ICI-myocarditis, specifically targeting them is important for treating this condition. 1 3 4 Abatacept dosing was assessed using threshold chosen for CD86RO (CD86RO≥80%) similar to those used in allograft rejection with belatacept and in rheumatoid arthritis with abatacept. 1 5 6 Using this strategy, abatacept dose used to reach CD86RO≥80% in our case was 4-6 times compared with dose used in RA within the two first weeks (three doses of 20 mg/kg herein vs 10 mg/kg in RA) and similar to that used for allograft rejection (three doses of belatacept 10 mg/kg within 2 weeks in rejection, with belatacept being twice more potent than abatacept in term of CD86RO). [START_REF] Geraud | Clinical pharmacology and interplay of immune checkpoint agents: a yin-yang balance[END_REF] Frequent immune-profiling revealed association between CD86RO and evolution of bio-clinical phenotypes (troponin-T, ECG, figure 2). We observed recurrences in sustained ventricular arrhythmias in the early management phases when CD86RO was <40%, emphasizing the link between CD86RO and cardiac arrhythmias, a hallmark of ICI-myocarditis. [START_REF] Power | Electrocardiographic manifestations of immune checkpoint inhibitor myocarditis[END_REF] Assessing CD86RO helped to precisely time the injections and dose of abatacept. Yet, numerous questions remain such as potential interacting elements altering abatacept-CD86RO relationship in ICI-myocarditis including concomitant intake of ipilimumab (anti-CTLA4) and remain to be determined in a future trial (NCT05195645).

Lastly, a major challenge to consider while treating patient with severe immune-related adverse events is how to mitigate the potential lethality associated with this side effect while preserving antitumor beneficial effects. Most immunossupressant have been flagged with a potential risk for protumorigenicity particularly when used chronically for years. 1 11 In our case, use of abatacept and ruxolitinib was the shortest possible and limited to less than a month; though associated with high-dose corticosteroids. We did observe a relapse of thymoma ~4 months after last anti-PD1 dose; and ~3 months after last abatacept/ruxolitinib dosing. This relapse was concurrent with re-expression of PD1 on T-cells and pembrolizumab blood level being undetectable suggesting a progressive vanish of ICI effect; but it is unclear to which extent the various immunossupressant drugs used to treat the ICI-myocarditis have contributed to this observation. Further research is indeed required to assess the question of the optimal drug mix, dosage and duration to be used to preserve ICI therapeutic effect while treating a severe ICI-related adverse event.

CONCLUSION

We present a case of quick reversal of pembrolizumabinduced fulminant life-threatening myocarditis, using personalized dose adapted immunosuppression based on abatacept, ruxolitinib and corticosteroids.

Figure 1

 1 Figure 1 Timechart of the evolution of tumor size, PD1 +T cells and pembrolizumab plasma concentration after injection, and through the myocarditis event. Thoracic CT-scanner images showing the thymoma 48 days before myocarditis (ie, 34 days before pembrolizumab) and 1year follow-up after pembrolizumab (maximal tumor size in mm) with the different anticancer treatment's subsequent sequences. Evolution over time of pembrolizumab circulating levels associated with proportion of T-cells expression PD1 (%) is also represented.

Figure 2

 2 Figure 2 ICI-myocarditis case report evolution on immunossupressant drugs. Timechart evolution of the patient (103 kg) with the main clinical events, treatments received and abatacept immune-monitoring results (circulating levels and CD86RO). CD86RO, CD86 receptor occupancy on circulating monocytes; (C) ICU, (cardiac). 99th percentile normal upper value of troponin-T was 14 ng/L; Hemodynamic support included extracorporeal life support associated with norepinephrine for the first 48hours. *For graphical representation, negative values of CD86RO were represented as null (see the Methods section for CD86RO value computation). ICI, immune checkpoint inhibitor; ICU, intensive care unit; LVEF, left ventricular ejection fraction; MMF, mycophenolate mofetil.

J Immunother Cancer: first published as 10.1136/jitc-2022-004699 on 5 April 2022. Downloaded from

Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

Competing interests Written consent for publication was obtained from the patient. J-ES have participated to advisory boards or consultancy from BMS, Novartis, Banook, AstraZeneca and Beigene. Other authors have nothing to disclose regarding this manuscript. SE received modest consultant fees from AstraZeneca, Amgen, BMS, Banook, Celgene and EISAI. J-ES, JM and YA have patents related to the treatment of ICI related immune adverse events. JM has served on advisory boards for Bristol Myers Squibb, Takeda, Audentes, Deciphera, Janssen, Immuno-Core, Boston Biomedical, Amgen, Myovant, Kurome Therapeutics, Star Therapeutics, ProtinQure, Pharmacyclics, Pfizer, Mallinckrodt Pharmaceuticals, Silverback Therapeutics, Cytokinetics, and AstraZeneca. JM was supported by National Institutes of Health grants (R01HL141466, R01HL155990, and R01HL156021).

Patient consent for publication Consent obtained directly from patient(s).

Ethics approval This study involves human participants and was approved by APHP-CSE-20-37_JOCARDITE.

Provenance and peer review Not commissioned; externally peer reviewed.

Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.