Y Lam

Catherine Neukirch

Christer Janson

Judith Garcia-Aymerich

Michael Clausen

N Sabrina Idrose

Pascal Demoly

Randi J Bertelsen

Lidia C Ruiz

Chantal Raherison-Semjen

Holly C Y Lam

Chantal Raherison

Deborah L Jarvis

Food hypersensitivity: an examination of factors influencing symptoms and temporal changes in the prevalence of sensitization in an adult sample

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

INTRODUCTION

Food hypersensitivity (FHS) refers to reproducible adverse reactions to food which clinically resemble allergy [START_REF]Food allergy-definition and classification[END_REF], covering food allergy and food intolerance. The prevalence of FHS has been estimated to be about 19.0% in the US [START_REF] Gupta | Prevalence and severity of food allergies among US adults[END_REF] and 2-37% across Europe [START_REF] Burney | The prevalence and distribution of food sensitization in European adults[END_REF][START_REF] Lyons | Food allergy in adults: substantial variation in prevalence and causative foods across Europe[END_REF][START_REF] Björnsson | Prevalence of sensitization to food allergens in adult Swedes[END_REF]. Although oral and skin symptoms were most commonly reported in Europe [START_REF] Lyons | Food allergy in adults: substantial variation in prevalence and causative foods across Europe[END_REF][START_REF] Falcão | Food hypersensitivity in Portuguese adults[END_REF][START_REF] Osterballe | The prevalence of food hypersensitivity in young adults[END_REF][START_REF] Patelis | Natural history of perceived food hypersensitivity and IgE sensitisation to food allergens in a cohort of adults[END_REF], about one in five adults with self-reported FHS also reported that they had experienced respiratory or cardiovascular symptoms as part of their reaction to food in their lifetime [START_REF] Lyons | Food allergy in adults: substantial variation in prevalence and causative foods across Europe[END_REF]. One study in the US showed that 51.1% of adults with symptoms highly suggestive of food allergy had experienced at least one severe reaction during their lifetime [START_REF] Gupta | Prevalence and severity of food allergies among US adults[END_REF].

Prediction of severe food reaction is difficult, as severity depends on a variety of food (e.g., allergens for food allergy) and host factors (such as sensitivity to allergens and severity of reactions to allergens) [START_REF] Turner | Can we identify patients at risk of life-threatening allergic reactions to food?[END_REF]. A prior clinical record of food reactions may predict severe reactions in the future, but a substantial proportion of people dying from food-related allergy had previously only presented with mild symptoms [START_REF] Turner | Can we identify patients at risk of life-threatening allergic reactions to food?[END_REF]. Better understanding of risk factors for severe food reactions may improve risk prediction and management. Previous studies have explored the risk factors of severe food allergic reactions, but some considered single outcome (e.g., only considered difficult breathing as outcome) [START_REF] Woods | International prevalences of reported food allergies and intolerances. comparisons arising from the European community respiratory health survey (ECRHS) 1991-1994[END_REF], or severe cases only [START_REF] Tanno | Foodinduced anaphylaxis morbidity: emergency department and hospitalization data support preventive strategies[END_REF], and some reported contradicting results (some suggested specific-IgE level predicts severity of symptoms while some did not) [START_REF] Benhamou | Correlation between specific immunoglobulin E levels and the severity of reactions in egg allergic patients[END_REF][START_REF] Anvari | IgE-mediated food allergy[END_REF]. Current evidence suggests that pre-existing respiratory conditions such as wheezing and asthma were more common in those reporting breathlessness as a characteristic of their food reactions [START_REF] Woods | International prevalences of reported food allergies and intolerances. comparisons arising from the European community respiratory health survey (ECRHS) 1991-1994[END_REF] and asthma was the main risk factor of food induced anaphylaxis and fatal food allergy [START_REF] Tanno | Foodinduced anaphylaxis morbidity: emergency department and hospitalization data support preventive strategies[END_REF].

Changes in sensitization to food with age [START_REF] Chiu | Sensitization to food and inhalant allergens in relation to atopic diseases in early childhood: a birth cohort study[END_REF] or over time in populations [START_REF] Mcgown | Changes in food-specific IgE over time in the National Health and Nutrition Examination Survey (NHANES)[END_REF] have been reported in children, but little is known about new onset FHS or changes in sensitization to food in adults. A large population-based survey in the US showed that about half of adults with self-reported food reactions which highly suggested allergies had developed symptoms with ingestion to at least one food item after 17 years old [START_REF] Gupta | Prevalence and severity of food allergies among US adults[END_REF]. A study using data from Sweden and Iceland (n = 807) reported the prevalence of sensitization to at least one food, and to peanut and soy in particular, decreased in adults over a 9-year period of follow-up even though the overall prevalence of reported FHS stayed the same [START_REF] Patelis | Natural history of perceived food hypersensitivity and IgE sensitisation to food allergens in a cohort of adults[END_REF]. However, this study only examined sensitization to six food items. There is little information on changes in the prevalence of sensitization to other food items in a wider adult population.

This study aims to improve the understanding of the characteristics of those with severe reactions following food ingestion by considering a wider range of health outcomes and population (i.e., allows comparisons between severe and less severe cases). This study also supplements the evidence on the changes in the prevalence of sensitization to the most common allergic food items among adults over time. Using information from a survey, conducted in a sample of the general adult population in Europe and Australia and collected as part of the European Community Respiratory Health Survey (ECRHS) III in 2010-2014, we identified the characteristics of participants who reported symptoms that were more likely to be associated with severe food reactions and examined the proportion of adult onset FHS (≥age 15). By linking information collected 10 earlier, we assessed the changes in prevalence of sensitization to food in this adult sample.

MATERIALS AND METHODS

Study participants

The ECRHS was established to examine the prevalence of asthma and identify its associated factors in European adult populations. The detailed study design was published elsewhere [START_REF] Burney | The European Community Respiratory Health Survey[END_REF]. In brief, a community based random sample of 1500 men and 1500 women aged 20-44 years old were recruited from each participating center (55 centers from 19 countries) in 1991-1993 (ECRHS I). After the completion of a short postal questionnaire in the first stage, a "random" sample of responders (300 men, 300 women randomly selected from the first stage sample) plus a sample about 150 of those reporting asthma symptoms in the postal questionnaire were invited for an interviewer-administered questionnaire and clinical assessment including venous sampling and skin prick test.

Two follow-ups were conducted for those who took part in the clinical assessment-ECRHS II (1998-2002) [START_REF]The European Community Respiratory Health Survey II[END_REF], and ECRHS III (2010-2014)-and these follow-ups included similar clinical assessments as ECRHS I. This analysis was restricted to the "random" sample of those who had took part in all follow-ups (ECRHS II to III, n = 5904, Supplementary Fig. 1) (see Appendix 1 in the Supplementary File for the number of participating centers and countries included for each analysis).

Informed consent was obtained from participants and ethics approval were granted from local ethics committees.

Information collected

Questions on FHS collected in ECRHS III were used in this analysis. Participants were asked specifically about reaction to each of the 25 core foods (Supplementary Table 1) and were then asked to identify three foods (not necessarily from the core foods) that caused the "main problem" (ordered by the food giving the most severe reaction), the type of selfreported symptoms (from a pre-defined list as shown in Supplementary Table 2), the time from ingestion to reaction and the age of the first episode.

Serum specific IgE to food was tested in most participants of ECRHS II (related to availability of residual serum) and participants in six countries in ECRHS III (related to available funds, see Appendix 1 in Supplementary File for list of countries included). Venous blood samples were taken with serum stored at -20 °C before being tested in the laboratory (Kings College London in 2002 for ECRHS II, and AMC Amsterdam in 2013/2014 for ECRHS III) using the Pharmacia CAP System (Phadia, Uppsala, Sweden). Samples were screened against five food mix groups (excp1, expc2, excp3, fx5 and fx6) consisting of the 25 core food items (Supplementary Table 1) and if positive (sIgE level ≥0.35 ku/l), tested for positivity for individual foods within the food mix group.

Serum sIgE level to house dust mite, cat and Timothy grass pollen were assessed using the Pharmacia CAP system in ECRHS II and III. Sensitization to birch was examined using skin prick test in ECRHS III (reagents and standard lancets from ALK-ABELLO. Refer to Appendix 2 in Supplementary File for details). A summary of ECRHS data used in this analysis is summarized in Supplementary Table 3.

Definitions used

FHS-a positive response to both questions "Have you ever had an illness or trouble caused by eating a particular food or foods?" AND "Have you nearly always had the same illness or trouble after eating this type of food?" (In Switzerland, the second question was omitted. FHS is defined as a positive answer to the first question AND the report of reaction to at least one individual food).

Severe food reaction-there is no single definition of severe food reaction. We defined severe reaction in this analysis with reference to the guidelines for diagnosing anaphylaxis. Symptoms that started within 4 h after ingestion of a particular food item and including at least one of the following:

(1) The presence of skin-mucosal symptoms (rash or itchy skin OR itching, tingling or swelling in mouth OR difficulty in swallowing) PLUS evidence of EITHER respiratory compromise (breathlessness) AND/OR a drop in blood pressure (dizziness and fainting) AND/OR severe gastrointestinal symptoms (diarrhea or vomiting) [START_REF] Turner | Time to revisit the definition and clinical criteria for anaphylaxis?[END_REF]. (2) In the absence of skin symptoms EITHER, a drop in blood pressure (dizziness and fainting), AND/OR respiratory compromise AND/OR laryngeal involvement (breathlessness) [START_REF] Turner | Time to revisit the definition and clinical criteria for anaphylaxis?[END_REF]. (3) The need for an "emergency injection".

Mild food reaction-any other symptoms reported after ingestion of food.

Sensitization to food and grass, cat, house dust mite-specific IgE greater than 0.35 kU/l to the allergens.

Positive skin prick test to birch-wheal size ≥3 mm for birch and positive control with no reaction to the negative control.

Asthma/nasal and skin allergies-a positive response to any of the questions "Have you ever had asthma?", "Do you have any nasal allergies, including hay fever?" and "Have you ever had eczema or any kind of skin allergy?".

Analysis

Associated factors of severe reactions. Using information at ECRHS III, we applied univariate analysis (chi-square test, Wilcoxon rank sum test or ttest, where appropriate) and multiple logistic regression to identify associations of severe food reactions with sex, age, self-reported asthma/ allergic (nasal and skin) history, total IgE level and sensitization to common inhalant allergens.

Age of onset of food reactions. Each participant reported details of up to three food-specific reactions. We firstly reported the proportion of participants with symptoms beginning (to any food) ≤15 years old, then described the median onset age of commonly reported foods.

Sensitization to food and severe symptoms. At ECRHS III, a subsample of 1673 participants had serum specific IgE measured for all 25 core foods. Among those reported FHS, we compared the proportion of positive IgE to the food between participants did and did not report severe symptoms using chi-square test.

Change of prevalence of sensitization to food. Sixteen hundred and twelve participants had food-specific serum IgE and specific IgE to inhalant allergens measured at both ECRHS II and ECRHS III. McNemar's test was used to compare the changes of the overall prevalence of sensitization (then by year-of-birth cohort for food). Wilcoxon signed-rank test was applied to compare the median of IgE level to food mix groups between ECRHS III and ECRHS II.

All statistical analyses were conducted using R 3.6.3 [START_REF] Core | R: a language and environment for statistical computing[END_REF]. A significance level of 0.05 was adopted in this analysis.

RESULTS

Sample

After excluding centers that did not ask the FHS questions (n = 871) and those who did not respond to the FHS questions (n = 168) in ECRHS III, 4865 participants between 38-67 years old (52.3% female) were included (see Supplementary Table 4 for detailed characteristics).

Prevalence of self-reported FHS and severe reactions

The prevalence of FHS (to any food) was 13.5% (655/4865) with 9.4% reporting FHS to at least one of the 25 core foods (Table 1). The prevalence of FHS was similar across age groups but was higher among females (16.9% vs. 9.7%, p < 0.0005). Among the 25 core foods, cow's milk (2.6%), Hazelnut (2.1%), apple (2.1%), kiwi fruit (1.9%) and shrimp or lobster (1.7%) were the most commonly reported food related to FHS. Oyster (0.67%) and strawberry (0.51%) were most commonly named among non-core foods. More details of prevalence (number) of FHS to core (non-core) foods are shown in Table 2 (Supplementary Table 5).

Of the 655 participants with self-reported FHS, 611 provided details of symptoms and were included in the symptom analysis. About one in four participants with self-reported FHS (26.4% of 611) reported symptoms suggestive of severe reactions. Breathlessness was the most commonly reported severe reaction (13.3%), followed by requiring emergency injection (9.5%) and skin-mucosal plus gastrointestinal symptoms (9.0%) (Table 1).

Age of onset of FHS Among the 596 participants reporting age of the first food reaction (any food), 76.5% had their first reaction at/after the age 15. These 596 participants reported a total of 1033 food-specific reactions (any food). About 81% of these 1033 were reported to have first occurred ≥15 years (78.0% for core food reactions). Among the most commonly reported foods, FHS triggered by fish had the lowest median age of first episode (20 years old, interquartile range IQR 10-37.2), while FHS related to peanut had the highest median age at 40 years old (IQR 27.5-45) (Fig. 1).

Risk factors for severe reactions

In univariate analysis, self-reported history of asthma, nasal allergies and skin allergies, being sensitized to house dust mite (but not to cat, grass or birch) and having a younger age of first episode of FHS were associated with severe reactions (p ≤ 0.05) (Table 3).

After adjusting for sex, country and factors identified in univariate analysis, self-reported asthma (OR 2.12 95% confidence interval (CI) 1.13, 3.44) and younger age of first reaction to any food (OR 1.02, 95% CI 1.01, 1.03 per year) remained significantly associated with severe reactions (Table 3).

Specific IgE

In ECRHS III, participants who had food-specific IgE measured (n = 1673) were slightly younger than those who did not have food-specific IgE measured (mean age 51.3 vs. 53.7 years old) but the prevalence of self-reported FHS was similar to that in the complete sample (14.4%).

The prevalence of sensitization to at least one of the five food mix groups was 14.8% (247/1673) (Supplementary Table 6). Among those sensitized and reported symptoms suggestive of FHS (n = 226), 69.5% (157/226) reporting mild reactions as defined (similar to that seen in the larger sample).

A total of 381 food-specific reactions were reported by these 1673 participants and 16.5% were sensitized to the relevant food (Supplementary Table 7). Among those with detailed symptom reported, the prevalence of sensitization to the relevant food was lower in those with severe reactions compared to those with milder reactions-but this difference, in this smaller sample, failed to reach conventional levels of statistical significance (6/54 vs. 39/ 183, p = 0.138) (Supplementary Table 7).

Changes in prevalence of sensitization

The prevalence of sensitization to at least one food mix group was 14.5% at ECRHS II and 15.9% at ECRHS III (n = 1612). This change is not statistically significant, but subgroup analysis shows a significant increase, from 13.3 to 16.0% (p = 0.019), for the cohort 1954-1963 (Table 4).

Prevalence of sensitization increased for food mix group epcx3 (banana, kiwi fruit, apple, peach, melon) from 9.3 to 12.0% (p = <0.0005) (Table 5). There were no significant changes in other food mix groups. The prevalence of sensitization to melon, a food item in epcx3, showed the largest increment among all core foods tested (0.7-2.6%), and although numbers were small, this was apparent in all six countries included (data not shown).

Median of IgE level to food mix group epcx1, epcx 2, epcx 3 and fx5 increased slightly from ECRHS II to III while IgE level to fx6 remained unchanged (Supplementary Table 8).

As has been previously reported in the entire ECRHS sample [START_REF] Amaral | Changes in IgE sensitization and total IgE levels over 20 years of follow-up[END_REF], we observed that the prevalence of IgE sensitization to house dust mite, grass and cat fell slightly between ECRHS II and ECRHS III (Table 5).

DISCUSSION

In this large multicentre epidemiological study based on selfreported symptoms and objective markers of IgE sensitization to some foods, we show that 13.5% of adults reported having FHS. Most of these reactions were triggered by one of 25 core foods previously identified and began at/after the age of 15 years. On the basis of self-reported symptoms and/or use of an injection occurring within 4 h of ingestion, we estimated that about one in four of this group had ever experienced a severe reaction, with severe reactions being more common in those with a younger age of onset and those with asthma. In this sample, there is little evidence that the overall prevalence of sensitization increased in 10 years.

Our analysis showed that self-reported history of asthma is associated with reporting severe reactions. This agrees with findings in previous studies that wheezing and asthma were associated with respiratory symptoms in food reactions [START_REF] Woods | International prevalences of reported food allergies and intolerances. comparisons arising from the European community respiratory health survey (ECRHS) 1991-1994[END_REF] and that life-threatening manifestations of food anaphylaxis were usually caused by respiratory compromise [START_REF] Turner | Can we identify patients at risk of life-threatening allergic reactions to food?[END_REF].

We also found participants reporting an earlier age of onset of FHS were more likely to report symptoms that are suggestive of severe reactions. This may occur because our definition of FHS include food intolerance (rather than allergy) which is unlikely to be severe and is more common in adults [START_REF] Rentzos | Prevalence of food hypersensitivity in relation to IgE sensitisation to common food allergens among the general adult population in West Sweden[END_REF]. The late onset of reaction to milk in Fig. 1 may reflect the development of intolerance in later life. The result may also have occurred because those with earlier onset have lived longer with their condition and therefore had more time to experience a severe reaction. However, when we looked at the association of age of onset with the presence of severe reactions within more narrow age groups (<50, 50-59, ≥60 years), the associations remained in each group with similar magnitude.

It is interesting to observe that FHS triggered by peanut had a median age of onset at 40 years, and that kiwi-related FHS also had a high median age of onset, in Fig. 1. These FHS cases may be linked to cross reactivity with pollen (e.g., sensitization to Bet-v1 like homologs, class 2 allergens) which may explain the less severe symptoms compared to those caused by other allergens of peanut (like stable storage proteins) that are more severe and usually begin in childhood [START_REF] Alessandri | Molecular approach to a patient's tailored diagnosis of the oral allergy syndrome[END_REF].

Despite the minor increases in the median of IgE level of 4 out of 5 food mix groups, the overall prevalence of sensitization to food remained unchanged in the 10-year period across the 6 centers with available data. We are aware that one earlier report from the ECRHS looking at participants (n = 807) from only Iceland and Sweden suggested a 56% decrease in sensitization to food mix group fx5 between the first and second surveys [START_REF] Patelis | Natural history of perceived food hypersensitivity and IgE sensitisation to food allergens in a cohort of adults[END_REF]. We did not see a change in sensitization to fx5 when limiting our analysis to the Swedish and Icelandic samples over the study period (n = 550, result not shown). This is likely related to the different surveys considered (we compared the prevalence between ECRHS Fig. 1 The age of first episode of the most commonly reported FHS cases by food. The number on the boxes indicates the number of participants included for each food. III and II while they compared ECRHS II and I) and that there is some between country variation in baseline prevalence [START_REF] Burney | Prevalence and distribution of sensitization to foods in the European Community Respiratory Health Survey: a EuroPrevall analysis[END_REF].

To date, there are not many large studies reporting the proportion of severe food reactions, probably because of the discrepancies in defining symptoms and severity in different study centers, the difficulties in recruiting a representative sample and the issues in long-term follow-up. Our study included a large representative adult sample across Europe which could capture potential severe cases that were not presented in hospital or mortality data. The use of the same protocol across study sites reassures the consistency in measurements. The adoption of objective biomarkers and the diagnostic guideline of anaphylaxis for severe reactions will allow easy comparison with other studies. Our analysis also benefits from the 10-year dataset which allows the assessment of prevalence over time. However, we acknowledged the use of self-reported symptoms and proxies for respiratory and cardiovascular symptoms does compromise the accuracy of outcome measurement. Recall bias and cohort effect may have reduced estimation accuracy. Biomarkers measured at survey times may not reflect the biological conditions at the time of food attacks. This, and the fact that self-reported FHS largely over-diagnosed proven IgEdependent food allergy, may partly explain the low prevalence of sensitization to the food among those reported severe symptoms. Cohort effect detected should be considered with caution due to multiple testing. Finally, the power of food-specific analysis was also limited by sample size.

In conclusion, our study showed that one-quarter of the surveyed adults reporting FHS had reactions that can be linked to severe outcomes, with the history of asthma and a younger onset age of FHS as potential risk factors. Nearly 80% of the self-reported FHS in this adult sample developed at/after the age of 15 years old. There was no evidence of an increase in overall prevalence of sensitization to foods in this sample in the 10-year period.

a

  Severe: breathlessness, fainting or dizziness, emergency injection required or having both skin-mucosal and gastrointestinal symptoms.

Table 1 .

 1 Prevalence of self-reported food hypersensitivity (FHS) and the associated symptoms at ECRHS III (N = 4865).

	Number	% in all participants

a Among the 655 reported FHS, 611 had reported details of symptoms.

Table 2 .

 2 Prevalence of self-reported food hypersensitivity (FHS) and the number of participants who experienced severe symptoms.

	Food item	Self-reported FHS (N = 4865)
		n (prevalence %)		Those reporting any symptoms	Those reporting severe symptoms a
				n	n (% in those reporting symptoms)
	1	Cow's milk	128 (2.6%)	86	10 (11.63%)
	2	Hazelnut	102 (2.1%)	72	17 (23.61%)
	3	Apple	98 (2.1%)	58	9 (15.52%)
	4	Kiwi Fruit	92 (1.9%)	56	14 (25.00%)
	5	Shrimp or Lobster	80 (1.7%)	54	12 (22.22%)
	6	Walnut	66 (1.4%)	17	3 (17.65%)
	7	Peach	56 (1.2%)	18	5 (27.78%)
	8	Wheat	56 (1.2%)	26	5 (19.23%)
	9	Peanut	53 (1.1%)	23	5 (21.74%)
	10	Fish	49 (1.0%)	35	17 (48.57%)
	11	Hen's eggs	34 (0.7%)	23	3 (13.04%)
	12	Carrot	33 (0.7%)	13	3 (23.07%)
	13	Tomato	33 (0.7%)	18	1 (5.56%)
	14	Bananas	29 (0.6%)	19	2 (10.53%)
	15	Soybean	23 (0.5%)	8	2 (25%)
	16	Melon	21 (0.4%)	6	0 (0)
	17	Celery	16 (0.3%)	7	5 (71.43%)
	18	Lentils	14 (0.3%)	3	0 (0)
	19	Buckwheat	14 (0.3%)	4	1 (25%)
	20	Rice	13 (0.3%)	7	0 (0)
	21	Corn	12 (0.2%)	2	0 (0)
	22	Mustard seed	9 (0.2%)	3	1 (33.33%)
	23	Sesame seed	7 (0.1%)	5	1 (20.00%)
	24	Sunflower seed	6 (0.1%)	3	1 (33.33%)
	25	Poppy seed	5 (0.1%)	1	0 (0)

Table 3 .

 3 The associated factors of severity of symptoms (ECRHS III data).

		Self-report FHS	Symptoms (n = 611)		p value b (Mild vs.
			Mild a	Severe a	Severe)
					Univar b	Mult log c
	Number of participants	655 d	450	161
	Female, n (%)	430 (65.7%)	295 (65.56%)	101 (62.73%)	0.584	0.400
	Mean age in year (SD)	53.4 (7.06)	53.74 (7.15)	53.12 (6.69)	0.571
	Country, n (%)				0.061
	Australia	55 (8.4%)	40 (8.89%)	12 (7.45%)
	Belgium	62 (9.5%)	43 (9.56%)	12 (7.45%)		0.967
	Estonia	15 (2.3%)	12 (2.67%)	3 (1.86%)		0.604
	France	124 (18.9%)	86 (19.11%)	33 (20.50%)		0.255
	Iceland	64 (9.8%)	38 (8.44%)	23 (14.29%)		0.025
	Norway	76 (11.6%)	57 (12.67%)	16 (9.94%)		0.494
	Spain	40 (6.1%)	22 (4.89%)	18 (11.18%)		0.013
	Sweden	160 (24.4%)	121 (26.89%)	34 (21.12%)		0.954
	Switzerland	18 (2.8%)	-	-		-
	UK	41 (6.3%)	31 (6.89%)	10 (6.21%)		0.761
	Self-reported allergic history, n (%)
	Asthma	158 (24.1%)	87 (19.33%)	62 (38.51%)	<0.0005	0.002
	Nasal allergies including hay fever	370 (56.5%)	251 (55.78%)	107 (66.46%)	0.012	0.163
	Skin allergies, including eczema	379 (57.9%)	249 (55.33%)	109 (67.70%)	0.008	0.063
	Total IgE level in kU/l, Median (IQR)	30.81 (11.28, 82.03) e	28.13 (10.93, 74.10) f	42.23 (13.57, 101.17) g	0.080
	Sensitization, n (%)
	House dust mite	100/541 (18.48%)	59/384 (15.36%)	36/134 (26.87%)	0.005	0.124
	Cat	73/541 (13.49%)	48/384 (12.5%)	23/134 (17.16%)	0.228
	Grass	118/541 (21.81%)	83/384 (21.61%)	34/134 (25.37%)	0.478
	Birch	113/476 (23.74%)	83/337 (24.63%)	28/125 (22.40%)	0.707
	Age of first FHS to any food, Median (IQR)	25 (15, 40) h	26 (15, 40)	22 (10, 35)	0.001	0.006
	Number of years since the first food reaction	26 (12, 38)	24 (11, 37)	30 (19, 41.5)	<0.005
	Bold values identify statistical significance (p < 0.05).

FHS food hypersensitivity, IQR interquartile range, SD standard deviation. a Severe: breathlessness, fainting or dizziness, emergency injection required and have both skin-mucosal and gastrointestinal symptoms. Mild: rash or itchy skin, diarrhea or vomiting, runny or stuffy nose, severe headaches, itching, tingling or swelling in mouth, difficulty swallowing. b Univariate tests: t-test for age; chi-square test for prevalence; Wilcoxon rank sum test for total IgE level and age of first FHS. c Multiple logistic regression: factors with p < 0.05 in univariate tests were included. Sex and country were adjusted. d Among the 655 had self-reported FHS, 44 did not provide details of symptoms. e n = 541. f n = 384. g n = 134. h n = 596.

Table 4 .

 4 Prevalence of sensitization to a least one food at ECRHS II and III by birth cohort.

	Birth cohort	n	Prevalence of sensitization to at least	p of McNemar's test
			one food
			ECRHS II	ECRHS III
	All	1612	14.45%	15.88%	0.0849
	1944-1953	163	18.40%	15.60%	0.4795
	1954-1963	930	13.33%	16.02%	0.019
	1964-1973	519	15.22%	15.60%	0.874

BOLD: p values < 0.05.

Table 5 .

 5 Prevalence of sensitization to food and inhalant allergens at ECRHS II and ECRHS III.Food items are ranked by statistical significance of changes between the surveys (p value). BOLD: statistically significantly change in prevalence of sensitization between the two surveys (p < 0.05).

	n	Prevalence of sensitization %	p values of McNemar's test
		ECRHS II	ECRHS III

European Journal of Clinical Nutrition

DATA AVAILABILITY

The datasets generated during and/or analyzed during the current study are not publicly available due confidential agreement but are available from the corresponding author on reasonable request.

AUTHOR CONTRIBUTIONS

HCYL and DLJ designed the study. DLJ directed the study's implementation. HCYL conducted the statistical analysis. HCYL and DLJ prepared the first draft of the manuscript. All authors contributed in investigation and interpreted the results. All authors revised and approved the manuscript.

COMPETING INTERESTS

The authors declare no competing interests.

ADDITIONAL INFORMATION Supplementary information

The online version contains supplementary material available at https://doi.org/10.1038/s41430-023-01284-w.

Correspondence and requests for materials should be addressed to Holly C. Y. Lam.

Reprints and permission information is available at http://www.nature.com/ reprints Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.


Marie Kerbie Plaisy
email: marie-kerbie.plaisy@u-bordeaux.fr

Simon P Boni

Patrick A Coffie

Aristophane Tanon

Adoubi Innocent

Apollinaire Horo

Francois Dabis

Anne Bekelynck

Antoine Jaquet

François Dabis

Désiré Dahourou

Sophie Desmonde

Julie Jesson

Valeriane Leroy

Didier Koumavi Ekouevi

François Dabis

Renaud Becquet

Charlotte Bernard

Karen Malateste

Olivier Marcy

Elodie Rabourdin

Thierry Tiendrebeogo

Raoul Moh

Jean-Claude Azani

Jean Jacques Koffi

Eric Komena

Maika Bengali

Abdoulaye Cissé

Guy Gnepa

Eulalie Kangah

Corinne Moh

Jeanne Eliam

Ighovwerha Ofotokun

Noelle Benzekri

Geoffrey Goettlieb

Marcel Djimon Zannou

Armel Poda

Oliver Ezechi

Eugene Messou

Henri Chenal

Kla Albert Minga

Moussa Seydi

Ephrem Mensah

Caroline Yonaba

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Tossa

Marcelline D' Almeida

Jocelyn Dame

Sylvie Marie N'gbeche

Kouadio Kouakou

Madeleine Amorissani Folquet

François Tanoh Eboua

Fatoumata Dicko Traore

Agatha David

Elom Takassi

Barriers to early diagnosis of cervical cancer: a mixed-method study in Cote d'Ivoire, West Africa

Keywords: Cervical cancer, Advanced cervical cancer stages, Limited resources, Andersen model, Côte d'Ivoire, Mixed methods study

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

Introduction

The management of cervical cancer (CC) remains a major public health issue in developing countries, mainly due to advanced stage of the disease at diagnosis [START_REF]Cervical cancer screening in developing countries: report of a WHO consultation[END_REF]. Effective prevention strategies including vaccination against human papilloma virus (HPV), CC screening followed by treatment of pre-cancerous lesions are intended to reduce incidence and mortality of CC [START_REF] Canfell | Towards the global elimination of cervical cancer[END_REF][START_REF] Karimi-Zarchi | Can the prophylactic quadrivalent HPV vaccine be used as a therapeutic agent in women with CIN? A randomized trial[END_REF][START_REF] Allahqoli | Diagnosis of Cervical Cancer and Pre-Cancerous Lesions by Artificial Intelligence: A Systematic Review[END_REF][START_REF] Gaffikin | Visual inspection with acetic acid as a cervical cancer test: accuracy validated using latent class analysis[END_REF][START_REF] Peirson | Screening for cervical cancer: a systematic review and meta-analysis[END_REF]. Although the effectiveness and efficiency of preventive measures of CC have been widely demonstrated [START_REF] Giannini | Advances on Prevention and Screening of Gynecologic Tumors: Are We Stepping Forward?[END_REF], access to HPV vaccination and screening at population-wide level remains limited in developing countries, and most CC are diagnosed at an advanced stage [START_REF] Dunyo | Factors associated with late presentation of cervical cancer cases at a district hospital: a retrospective study[END_REF][START_REF] Mlange | Patient and disease characteristics associated with late tumour stage at presentation of cervical cancer in northwestern Tanzania[END_REF][START_REF] Gyenwali | Factors Associated with Late Diagnosis of Cervical Cancer in Nepal[END_REF]. According to the latest world cancer statistics, CC is the fourth most common diagnosed cancer and the fourth leading cause of cancer death in women worldwide, with approximately 604,000 new cases and 342,000 deaths. Sub-Saharan Africa accounts for the highest incidence and mortality, partly due to the lack of formalized screening programs [START_REF] Sung | Global Cancer Statistics 2020: GLOBOCAN estimates of incidence and Mortality Worldwide for 36 cancers in 185 countries[END_REF].

In Côte d'Ivoire, CC is the second most common cancer in women and the leading cause of cancer death in women. Age-standardized incidence and mortality rates are estimated at 31.2 cases and 22.8 deaths per 100,000 women in 2020, respectively [12]. Since 2009, the Ivorian Ministry of Health, through its National Cancer Control Program (PNLCa), has implemented a national program for CC screening and subsequent treatment of precancerous lesions, which are based on visual inspection with acetic acid and cryotherapy, respectively. This screening program has been subsequently scaled-up over 134 healthcare facilities. Nevertheless, as reported by a previous study, screening coverage for CC remains relatively low with a rate of only 1.2% in the urban area of Abidjan; and aproximately 70% of CC were diagnosed at an advanced stage [START_REF] Tanon | The Spectrum of Cancers in West Africa: Associations with Human Immunodeficiency Virus[END_REF][START_REF] Boni | Assessment of the scale-up of cervical cancer screening in Abidjan stratified by HIV status[END_REF]. This is a serious concern, given the fact that CC is highly preventable and curable if detected and treated in the earliest stage [START_REF] Canfell | Towards the global elimination of cervical cancer[END_REF]. Of note, in high-income countries, organised and comprehensive approaches to cervical screening and prophylactic treatment have significantly reduced the incidence and mortality of CC over the past decades [START_REF] Forman | Global Burden of Human Papillomavirus and Related Diseases[END_REF][START_REF] Taylor | Effects of screening on cervical cancer incidence and mortality in New South Wales implied by influences of period of diagnosis and birth cohort[END_REF][START_REF] Vaccarella | 50 years of screening in the nordic countries: quantifying the effects on cervical cancer incidence[END_REF].

Early diagnosis of CC is of far greater prognostic importance than any attempts to treat the disease at an advanced stage, as at this stage, treatment is more challenging and the risk of early cancer-related mortality is increased [START_REF]Cancer survival in England: national estimates for patients followed up to 2017[END_REF][START_REF] Chopra | Locally advanced cervical cancer: a study of 5-year outcomes[END_REF]. Beyond the WHO call for elimination targeting 90% of women diagnosed with CC accessing care, access to an effective treatment is therefore largely mediated by the extension of the disease when diagnosed [START_REF] Who | Global strategy to accelerate the elimination of cervical cancer as a public health problem[END_REF]. Accordingly, it is crucial to have a better understanding of factors associated with advanced stages of CC considering the limited information from low and middle-income countries [START_REF] Dunyo | Factors associated with late presentation of cervical cancer cases at a district hospital: a retrospective study[END_REF][START_REF] Mlange | Patient and disease characteristics associated with late tumour stage at presentation of cervical cancer in northwestern Tanzania[END_REF][START_REF] Zeleke | Factors Associated with Delayed Diagnosis of Cervical Cancer in Tikur Anbesa Specialized Hospital, Ethiopia, 2019: Cross-Sectional Study[END_REF][START_REF] Mwaka | Social, demographic and healthcare factors associated with stage at diagnosis of cervical cancer: cross-sectional study in a tertiary hospital in Northern Uganda[END_REF][START_REF] Benemariya | Perceived factors for delayed consultation of cervical cancer among women at a selected hospital in Rwanda: An exploratory qualitative study[END_REF]. The aim of this study was to determine the barriers to early diagnosis of CC in Côte d'Ivoire.

Materials and methods

Population and design

A cross-sectional study using a mixed quantitative and qualitative method was conducted in Abidjan, the economic capital of Côte d'Ivoire from July 2018 to June 2019. Our study population was nested in a larger project supported by the cancer registry of Abidjan that initiated a rapid case ascertainment of all CC diagnosed in the urban area of Abidjan during a two-year period. During this period, all units potentially managing CC from the public sector (four units from the three public referral hospitals in Abidjan and the recently opened radiotherapy center), as well as one of the major clinics from the private sector with the capacity to manage CC in the urban area of Abidjan, were asked to systematically include all adult women aged ≥ 18 years old with a suspected or confirmed diagnosis of CC. Cervical biopsies and histologic examination by the local pathology unit were systematically proposed and financially supported by the research project, when appropriate. For the purpose of the study, we included all women diagnosed with CC and being alive during the study period. Women who where unable to participate due to an impaired physical health condition, or who refused to participate in our study or could not be reached by telephone during our study period were excluded.

Collected information

Trained clinical monitors administered a structured questionnaire to women enrolled in this research project to collect clinical and sociodemographic characteristics such as age, formal education (categorized as no school, primary school, secondary school and above), parity, personal monthly income, personal health insurance coverage. Clinical stage of cancer at CC diagnosis was assessed based on the International Federation of Gynecology and Obstetrics (FIGO) staging system [START_REF] Bhatla | Revised FIGO staging for carcinoma of the cervix uteri[END_REF]. Based on available information after the initial assessment of the tumor extension, clinical stage at diagnosis was reported by clinicians and dichotomized as early (stage I and II) or advanced (stage III and IV) disease.

A nationally approved rapid HIV test (Determine, Abbott Diagnosis) was systematically performed by collecting capillary blood through a finger prick during the interview. In case of positive result, a venous blood sample was collected for confirmation purposes in accordance with the national algorithm of Côte d'Ivoire.

From May to July 2019, all women included in this rapid case ascertainment study were systematically contacted by phone to obtain additional information as part of the present study. From all participants who consented to participate in the study, a sample of 12 women was selected for semi-structured interviews. They were selected purposively based on different characteristics such as age, HIV status, place of residence, International Federation of Gynaecology Obstetrics (FIGO) stage and level of education to obtain a diversified profile that reflects the caracteristics of the overall enrolled participants. The number was determined on the principle of data saturation. Additional interviews were conducted with Key Informants (KIs), including health professionals (n = 5) and public stakeholders (n = 1) worked at the participating cancer referral hospitals.

We administrated a standardized questionnaire faceto-face at the referral hospital where the patients were diagnosed for CC, and by phone for participants who could not attend in person to collect data as part of the quantitative component of the study. With regard to the qualitative component, all semi-structured interview were carried out face-to-face using an interview guide.

The questionnaire was designed based on the Andersen's model (Fig. 1) and findings from studies on factors contributing to advanced CC stages in low and middleincome countries [START_REF] Mlange | Patient and disease characteristics associated with late tumour stage at presentation of cervical cancer in northwestern Tanzania[END_REF][START_REF] Gyenwali | Factors Associated with Late Diagnosis of Cervical Cancer in Nepal[END_REF][START_REF] Mwaka | Social, demographic and healthcare factors associated with stage at diagnosis of cervical cancer: cross-sectional study in a tertiary hospital in Northern Uganda[END_REF][START_REF] Benemariya | Perceived factors for delayed consultation of cervical cancer among women at a selected hospital in Rwanda: An exploratory qualitative study[END_REF][START_REF] Walter | The Andersen Model of Total Patient Delay: a systematic review of its application in cancer diagnosis[END_REF]. The Andersen's model was designed to describe the decision and behavioural processes that occur prior to the diagnosis and treatment of cancer and other chronic conditions [START_REF] Walter | The Andersen Model of Total Patient Delay: a systematic review of its application in cancer diagnosis[END_REF]. This model was adapted and we considered the intervals for symptom appraisal, care seeking and total time that can influence the diagnosis of CC. The questionnaire included questions on socio-demographics, health insurance coverage, access to traditional healers, access to specialized facilities, prior knowledge of CC, past history of cervical screening, history of the disease including the intervals based on Andersen's model (symptom appraisal, care seeking and total time) and the pre-referral consultations. The symptom appraisal interval is defined as the time between detection of unexplained symptoms and the decision to consult a healthcare provider. The care seeking interval is the time between the first symptoms dectected and the first consultation to a healthcare provider. The total time interval represents the time between the first symptoms and the histological diagnosis of CC [START_REF] Walter | The Andersen Model of Total Patient Delay: a systematic review of its application in cancer diagnosis[END_REF][START_REF] Ouasmani | The Measurement of Delay in Diagnosis and Treatment among Moroccan Women with Cervical Cancer[END_REF][START_REF] Scott | The model of pathways to treatment: conceptualization and integration with existing theory[END_REF]. (See Fig. 1). Pre-referral consultations is defined as any visit to a healthcare provider before the diagnosis of CC [START_REF] Lyratzopoulos | Measures of promptness of cancer diagnosis in primary care: secondary analysis of national audit data on patients with 18 common and rarer cancers[END_REF]. The qualitative interview guide included questions related to gynecological follow-up prior to CC diagnosis, therapeutic pathway leading to CC diagnosis, various obstacles to seeking care and getting a diagnosis, cultural and religious beliefs regarding CC, cervical screening and diagnosis services in Côte d'Ivoire, with suggestions to improve the quality of such services. Time taken for each interview was about 30 to 50 min, and interviews were recorded using a dictaphone.

Mixed methods data analysis

In the quantitative analysis, continuous variables were presented as median with their interquatile range (IQR) and categorical variables as absolute numbers and percentages (%). The measured outcome was CC stage at diagnosis dichotomised as early (stage I and II) or advanced (stage III and IV). To determine factors associated with advanced CC stages, univariable and multivariable logistic regressions were performed. Variables found be associated (p value ≤ 0.20) with advanced CC stages in univariable models were entered into the initial multvariable model. A stepwise descending procedure was performed to obtain the final model. Both unadjusted (UOR) and adjusted Odd's ratios (AOR) were computed together with their 95% confidence limits (95% CI). A p-value of ≤ 0.05 was considered significant in the final model. The variable Knowledge of CC was not significant but remained in the model as a confounding variable for HIV status and Health insurance covariates. All statistical analysis were performed using the Version 3.5.0 of the R software.

For the qualitative component, all interviews were manually transcribed from Microsoft Word the day of the interview. Data were analyzed using thematic analysis technique with the aid of QDA miner Lite software. Guided by the Model of Pathways to Treatment, themes and sub themes have been identified, indexed, interrelated and described. These were then colour-coded, quotations were selected to represent each emerging theme and are reported as the study results [START_REF] Vaismoradi | Theme development in qualitative content analysis and thematic analysis[END_REF][START_REF] Buetow | Thematic analysis and its reconceptualization as "saliency analysis[END_REF]. We further triangulated qualitative themes and quantitative data to identify areas of convergence and divergence related to factors contributing to an advanced CC stages at diagnosis. In the results section of the manuscript, verbatim quotes from participants were identified by numbers, participant age in year, and FIGO stage. However, information from Keys Informants served to guide the interpretation and discussion of our findings.

Results

Respondents' characteristics

A total of 158 women with a histological diagnosis of CC between July 2018 and June 2019 were identified by the Abidjan cancer registry and requested through phone calls to participate in our study. Of these, 50 died before the period of our survey. Among the 108 alive, 13 were excluded for the following reasons: unreachable by phone (n = 6), refusal (n = 3), unaware of their disease (n = 1) or FIGO not available in the medical records (n = 3). Thus, 95 women were included in our quantitative analyses.

Their median age was 51 (IQR 42-59) years. About two third 61 (64.2%) were unmarried; 41 (43.2%) lived in Abidjan; 33 (34.7%) had no monthly income and 54 (56.8%) had monthly income less than 250 USD. Forty four women (46.0%) reported no formal education; 39 (41.1%) were unemployed and 55 (57.9%) were diagnosed with CC six months or more after the onset of the first symptoms. HIV infection was found in 18 (18.9%) respondents and only 9 (9.5%) were covered by a health insurance. Approximately 62 (65.3%) of the participants in our study had three or more consultations prior CC confirmation. All participants in our study were diagnosed with CC based on the occurrence of pre-exisiting signs and symptoms. An advanced CC stage at diagnosis was reported in 68 (71.6%) respondents and majority of them had squamous cell carcinomas 86 (90%) (Table 1).

A total of 18 semi-structured interviews were conducted as part of the qualitative component; 12 with women diagnosed with CC and 6 with key informants (KIs), i.e. health professionals and public stakeholders. Most of the women involved in the qualitative survey lived in Abidjan (8/12). Half of them reported no formal education and low economic level (those with a monthly income of less than 250 $USD). Four of them were infected with HIV at the time of CC diagnosis and 8 were diagnosed with advanced CC (FIGO III or IV). (Table 2). All KIs respondents were working at health facilities in Abidjan. Among them, two were oncologists of which one also worked at the PNLCA, two KI were gynaecologists and practiced respectively at the university hospital and general hospital, and two were midwives. (Table 3).

Factors associated with advanced cervical cancer Patient related factors

In the multivariable model, HIV-uninfected respondents were more likely to have advanced CC than those HIV-infected (AOR = 5.4; 95% CI [1.6-17.8], p = 0.006). (Table 4).

In-depth interviews showed that it is not usual for healthy ivorian women to have regular gynaecological follow-up. However, patients with a chronic disease, such as HIV, are more likely to be tested early within the management of their disease according to national guidelines. Being uninsured was significantly associated with advanced CC (AOR = 13.1, 95% CI [2.0-85.5], p = 0.007) (Table 4). In-depth interviews, lack of money was mentioned by most respondents as a major cause of delay in performing the test required to confirm the diagnosis of CC. One participant mentioned that she was privileged to perform the biopsy early and to be diagnosed at an early stage of the disease through her health insurance.

"... I used to get tested for cervical cancer every year at the HIV clinic where I received my medication. The last time was in 2017. " (P6, 38 years old, stage I) "Before the illness, I didn't use to consult the gynae-

"Biopsy is still expensive. I was lucky enough to have it done the same day it was prescribed and to be diagnosed at an early stage because my insurance covered more than half of the costs. " (P11, 38 years old, stage II) "I couldn't do the biopsy the same day it was prescribed because of lack of money. So I waited two weeks before coming back to do it for free at the university hospital. " (P7, 36 years old, stage III)

Participants who attended directly to specialized facilities were more likely to be diagnosed with advanced CC compared to those who had been referred by peripheral healthcare providers (AOR = 7.05, 95% CI [1. .07], p = 0.03).

During our in-depth interviews, some participants reported that the main reason they attended specialized facilities directly was related to the deterioration of their health conditions as they were not familiar with CC and its treatment when the disease first appeared.

"At the beginning, I didn't consider my illness, I thought it was common. It was a few months later, when I saw that I was bleeding too much and becoming very weakened, I went directly to the university hospital. " (P1, 59 years old, stage III)

Statistically significant association was not found between the total number of pre-diagnosis visits (OR = 0.9, 95% CI [0.3-2.3], p = 0.85), total time interval (OR = 0.7, 95% CI [0.3-1.8], p = 0.52, histologic type (OR = 0.3, 95% CI [0.0-2.4], p = 0.25) and advanced CC stages. (Table 4).

Health providers-related factors

In-depth interviews highlighted the role of healthcare providers in the diagnosis of advanced CC stages. Two sub-themes were identified as priorities: lack of patient information and awareness about CC, and inadequate knowledge on signs and symptoms of CC.

Lack of patient information and awareness about cervical cancer and screening by healthcare providers

Some participants reported that the physicians they had consulted prior to the beginning of their disease were partly responsible for the advanced stage of their cancer. They mentioned that they had never been informed about CC, or been proposed the screening test during their previous medical visits. For others participants, while information about CC was provided and CC screening was proposed by physicians, the information appeared to be unclear and not explicit. During the interview, a respondent mentioned not understanding the benefits of the test, nor the gravity of the disease and, therefore did not return for the follow-up. This would have contributed to poor uptake or adherence to the screening test, leading to advanced stages of CC at diagnosis.

"

Inadequate knowledge of the signs and symptoms of cervical cancer

Some respondents mentioned that some healthcare providers appear to be unfamiliar with the signs and symptoms of CC. This sometimes leads to misdiagnosis and inappropriate management, which can be a barrier to early diagnosis of CC.

Health system factors

Inadequate national awareness and screening campaigns

Inadequate national awareness and screening campaigns were mentioned as a barrier to early diagnosis of CC, as exemplified by the women in our study. Some women elaborated the poor distribution of these campaigns, which are more concentrated in large cities than in villages. They also reported the irregularity of these campaigns, the ambiguity of the information provided, and the lack of CC awareness campaigns compared to other diseases. The unsuitability of communication tools within the local context was also emphasized by some respondents.

"[…]

There is more awareness campaigns on breast cancer than cervical cancer. Those who talk about cervical cancer don't give enough information about its causes and symptoms. " (P12, 49 years old, stage IV) "I have heard that the message about cervical cancer and screening is played only on the radio. However, in my village, I don't have a radio. That's why I didn't have access to information about it before my illness. " (P4, 34 years old, stage III)

Discussion

To the best of our knowledge, this is the first study conducted in Côte d'Ivoire to identify barriers to early diagnosis of CC. Our findings showed that some characteristics related to patients (HIV-uninfected, being uninsured), healthcare providers (inadequate knowledge of the signs and symptoms of CC, lack of patient information and awareness about CC), and the health system (inadequate awareness and screening campaigns) were higlighted as potential drivers of advanced CC stages at diagnosis. In our study, more than two-thirds of respondents were diagnosed with advanced CC. This finding is consistent with other studies conducted in Sudan (71.5%) [START_REF] Ibrahim | Predictors of cervical cancer being at an advanced stage at diagnosis in Sudan[END_REF] and Abidjan (70.0%) [START_REF] Tanon | The Spectrum of Cancers in West Africa: Associations with Human Immunodeficiency Virus[END_REF]. Based on the litterature, CC diagnosed at an advanced stage is associated with adverse complications, poor treatment outcomes, and high mortality rate [START_REF]Cancer survival in England: national estimates for patients followed up to 2017[END_REF][START_REF] Cohen | Cervical cancer[END_REF]. This study showed that women who did not have medical insurance were more likely to be diagnosed at an advanced CC stages than those who had medical insurance. Similar finding was also reported in Sudan, showing a correlation between lack of health insurance and advanced CC (OR = 7.7; [3.76-15.38]) [START_REF] Ibrahim | Predictors of cervical cancer being at an advanced stage at diagnosis in Sudan[END_REF]. Based on our findings, lack of health insurance can hinder some ivorian women to attend the hospital for a medical check-up or in case of illness, and to afford the medical fees. In Côte d'Ivoire, the overall costs for CC diagnosis, including consultation and biopsy fees, is quite expensive. As reported by the PNLCa, patients could pay between 34 and 37 $USD in the public sector; and between 59 and 76 $USD in the private sector. Understandably, this could be a financial barrier for most ivorian women and could delay the realization of the biopsy to confirm the CC. Our study revealed that few of the participants were covered by health insurance. Access to universal health coverage in Côte d'Ivoire might reduce social health inequalities, advanced CC stages and others chronic conditions, and address the health needs of the ivorian population. Several studies have shown the positive effect of health insurance on the early diagnosis of some cancers (breast, colon, lung, uterus, prostate) [START_REF] Lukavsky | Insurance status effects on stage of diagnosis and surgical options used in the treatment of breast cancer[END_REF][START_REF] Lin | Early-and late-stage Cancer diagnosis under 3 years of Medicaid Expansion[END_REF][START_REF] Yabroff | Health Insurance Coverage Disruptions and Cancer Care and Outcomes: Systematic Review of Published Research[END_REF]. In line with others studies, HIV-infected participants were diagnosed with CC at an earlier stage than did their uninfected counterparts. This statement is consistent with results of two studies performed in Uganda and Bostwana [START_REF] Menon | Association between HIV infection and Cancer Stage at Presentation at the Uganda Cancer Institute[END_REF][START_REF] Rendle | Patient perspectives on delays in cervical cancer screening and followup care in Botswana: a mixed methods study[END_REF]. It is mainly related to the lack of access to healthcare and/or poor services especially in public facilities in limited-income countries. Because of inadequate access to healthcare, women in the general population have no incentive to perform gynaecological follow-up and consult a physician at the onset of signs and symptoms for an early diagnosis. On the other hand, HIV-infected women are more likely to be diagnosed at an early stage, as CC screening has been increasingly integrated into the package of services for HIV-infected women over the past decade, ensuring a better protection towards advanced stages. In line of this finding, integration of CC screening programs into other pre-existing care systems could improve access and quality of care, by providing a holistic care to all patients attending the health facility [START_REF] Gounder | A diagonal approach to building primary healthcare systems in resource-limited settings: women-centred integration of HIV/ AIDS, tuberculosis, malaria, MCH and NCD initiatives[END_REF][START_REF] Nigatu | Integration of HIV and Noncommunicable Diseases in Health Care Delivery in Low-and Middle-Income Countries[END_REF][START_REF] Temu | Integration of non-communicable diseases in health care: tackling the double burden of disease in African settings[END_REF].

Results of our study showed that participants who came directly to specialized facilities were more likely to be diagnosed at an advanced stage than those who had been quickly referred by peripheral healthcare providers. This is considered as a consequence of the advanced stage of CC, as most of the women who came directly to a specialized facility presented a deteriorating conditions, and most of them were diagnosed at an advanced stage. This finding could be explained by women's limited knowledge and awareness about the signs and symptoms of CC and/or inadequate management of their symptoms during the previous visits. Furthermore, results of our qualitative approach suggest that inadequate knowledge of the signs and symptoms of CC, especially among primary healthcare providers, leading to misdiagnosis and inappropriate management. This statement is consistent with results from two studies conducted in Rwanda and Malawi [START_REF] Benemariya | Perceived factors for delayed consultation of cervical cancer among women at a selected hospital in Rwanda: An exploratory qualitative study[END_REF][START_REF] Chadza | Factors that contribute to delay in seeking cervical cancer diagnosis and treatment among women in Malawi[END_REF]. Aside from the gap in CC knowledge, some healthcare providers do not inform their patients about CC and the screening procedures. This may reflect the limited effectiveness of the CC screening programs implemented by the ivorian ministry of health that have so far. Lack of knowledge and awarness towards CC screening surely contributes to the underuse of CC screening services, a key factor in the prevention of advanced CC diagnosis. Indeed, a few of the participants in our study had been screened for CC prior to their illness. Previous studies in Ghana and Iran have demonstrated a significant association between lack of CC screening and advanced CC stage [START_REF] Dunyo | Factors associated with late presentation of cervical cancer cases at a district hospital: a retrospective study[END_REF][START_REF] Behnamfar | Factors associated with delayed diagnosis of cervical cancer in Iran-a survey in Isfahan City[END_REF].

These findings showed that significant efforts through the implementation of early CC surveillance programs, including public awareness and health providers' education about the disease could reduce the proportion of advanced CC. Accordingly, results of a pilot program in Malaysia, which focused on women's and health professionals' education, showed a significant reduction in advanced cervical and breast cancers, along with a significant cost-effectiveness [START_REF] Devi | Reducing by half the percentage of late-stage presentation for breast and cervix cancer over 4 years: a pilot study of clinical downstaging in Sarawak, Malaysia[END_REF]. Results from others studies have shown that large-scale interventions, including public awarness and education, have reduced the proportion of cancer diagnosed at an advanced stage [START_REF] Kennedy | Lung cancer stage-shift following a symptom awareness campaign[END_REF][START_REF] Saab | Promoting lung cancer awareness, help-seeking and early detection: a systematic review of interventions[END_REF].

Our quantitative results revealed no association between total time interval prior CC diagnosis and advanced CC. The same result was found in a study conducted in northern Uganda [START_REF] Mwaka | Social, demographic and healthcare factors associated with stage at diagnosis of cervical cancer: cross-sectional study in a tertiary hospital in Northern Uganda[END_REF]. All participants in our study were diagnosed with CC based on preexisiting signs and symptoms. Most of them were at an advanced stage at the time of recognition of these signs and symptoms as abnormal, regardless of the number of pre-diagnosis visits and the total time interval. These results confirmed that access to a systematic CC screening remains a key determinant to reduce the proportion of advanced CC, as mentioned above.

The current study has some limitations to consider. A significant number of women initially enrolled in the cancer registry project had died by the time our survey was conducted. Moreover, some suspected cases identified outside of Abidjan could not reach the town to confirm the diagnosis of CC through biopsy. This could potentially underestimate the proportion of CC diagnosed at an advanced stage. However, the proportion of women with advanced CC is quite similar to findings from previous studies in Côte d'Ivoire and sub-Saharan African countries [START_REF] Tanon | The Spectrum of Cancers in West Africa: Associations with Human Immunodeficiency Virus[END_REF][START_REF] Mwaka | Social, demographic and healthcare factors associated with stage at diagnosis of cervical cancer: cross-sectional study in a tertiary hospital in Northern Uganda[END_REF][START_REF] Ibrahim | Predictors of cervical cancer being at an advanced stage at diagnosis in Sudan[END_REF]. Retrospective recall bias could have been introduced when determining the exact time intervals between the onset of symptoms and the diagnosis. It was often difficult for participants to accurately determine the date of the onset of their symptom, or to recognize whether the symptoms were actually associated with CC. However, in such a mixed-methods study, the inability to accurately determine the intervals of symptom onset, care-seeking, and total time could not affect participants' perceptions of the therapeutic pathway leading to CC diagnosis.

Conclusion

Factors facilitating access to healthcare system prior to the diagnosis of CC, including being insured, availability of a vertical healthcare program as HIV, tend to be protective factors for diagnosis of advanced CC in Côte d'Ivoire. Qualitative interviews with women diagnosed with CC and key informants revealed several gaps in knowledge about CC and its prevention. Further studies involving primary care workers are needed to confirm their potential role in the diagnosis of advanced CC. Improvement of the existing education and awareness raising programs targeting women and healthcare providers should also be considered, and its impact on advanced CC stages should be explored.

In addition, large-scale awareness and education campaigns are needed to promote access to systematic CC screening and to improve the ongoing training of healthcare providers, especially primary care providers, to reduce advanced CC stages. Moreover, findings of this study highlight the urgent need to implement an inclusive health insurance system which contributes to the early detection of CC and the reduction of health inequalities towards the elimination of CC, a WHO target by 2030.

List of abbreviations

Fig. 1

 1 Fig. 1 Conceptual framework of the study based on Andersen model and data from the literature

Table 1

 1 Characteristics of 95 women diagnosed with cervical cancer in Côte d'Ivoire, 2019

	Characteristics	Early stage (n = 27)	Advanced stage (n = 68)	Total (n = 95)
		n	%	n	%	n	%
	Age, median [IQR]	49	[41-57]	52	[42-60]	51	[42-59]
	Age group (years)
	<40	5	18.5	12	17.6	17	17.9
	40-59	18	66.7	37	54.4	55	57.9
	≥60	4	14.8	19	27.9	23	24.2
	Education level
	None	11	40.7	33	48.5	44	46.3
	Primary	8	29.6	20	29.4	28	29.5
	Secondary and over	8	29.6	15	22.0	23	24.2
	Marital status
	Married	12	44.4	22	32.4	34	35.8
	Widowed	5	18.5	20	29.4	25	26.4
	Living with partner	6	22.2	12	17.6	18	18.9
	Single or divorced	4	14.8	14	20.6	18	18.9
	Occupation
	Employed	17	63.0	39	57.4	56	58.9
	Unemployed	10	37.0	29	42.6	39	41.1
	Number of biological children
	< 5	12	44.4	31	45.6	43	45.3
	≥5	15	55.6	37	54.4	52	54.7
	HIV status
	Positive	9	33.3	9	13.2	18	18.9
	Negative	18	66.7	59	86.8	77	81.1
	Place of living
	Abidjan	10	37.0	31	45.6	41	43.2
	Other cities $	17	63.0	37	54.4	54	56.8
	Health Insurance coverage
	Insured	6	22.2	3	4.4	9	9.5
	Uninsured	21	77.8	65	95.6	86	90.5
	Monthly income (USD)
	None	8	29.6	25	36.8	33	34.7
	<250	14	51.9	40	58.8	54	56.8
	≥250	5	18.5	3	4.4	8	8.4

Estimated distance from home to referral hospital (Kilometers)

	< 100	12	44.4	36	52.9	48	50.5
	≥ 100	15	55.6	12	47.1	47	49.5
	Histological subtypes
	Adenocarcinoma	1	3.7	8	11.8	9	9.5
	Squamous cell carcinoma	26	96.3	60	88.2	86	90.5
	Total time interval® (days)
	Median, [IQR]	231	[120-379]	208	[113-439]	216	[117-429]
	< 180	10	37.0	30	46.1	40	42.1
	≥ 180	17	63.0	38	53.9	55	57.9
	Number of pre-diagnosis visits
	Median, [IQR]	3	[2-4]	3	[2-4]	3	[2-4]
	<3	9	33.3	24	35.3	33	34.7
	≥3	18	66.7	44	64.7	62	65.3

Notes: ®, time between the first symptoms and the histological diagnosis of cancer; $, people who lived in other districts of Côte d'Ivoire except Abidjan cologist because I had no disease. " (P2, 38 years old, stage IV). "Africans do not visit gynaecologist except for childbirth or other serious health problems. And often, in our culture, we say to avoid waking up the sleeping illness. Laughing. " (P8, 43 years old, stage III)

Table 2

 2 Characteristics of women interviewed in the qualitative component, Côte d'Ivoire, 2019

	Participant	Age (years) City of residence	Education level Socio-Eco-	HIV Status	Health	FIGO
					nomic Status		Insurance	stage
	P1	59	Abidjan	Primary	Low	Negative	Uninsured	III
	P2	38	Lagunes	None	Low	Negative	Uninsured	IV
	P3	54	Abidjan	None	Very Low	Positive	Uninsured	IV
	P4	34	Abidjan	None	Very Low	Negative	Uninsured	III
	P5	56	Zanzan	None	Low	Negative	Uninsured	III
	P6	38	Abidjan	None	Low	Positive	Insured	I
	P7	36	Abidjan	None	Very Low	Negative	Uninsured	III
	P8	43	Bas-Sassandra	Primary	Low	Negative	Uninsured	III
	P9	43	Abidjan	Primary	Low	Positive	Uninsured	II
	P10	49	Comoé	Primary	Very Low	Positive	Uninsured	II
	P11	38	Abidjan	Secondary and	Medium	Negative	Insured	II
				over
	P12	49	Abidjan	Secondary and	Medium	Negative	Uninsured	IV
				over

Abbreviations: FIGO-International Federation of Gynaecology and Obstetrics; P-Participant Notes: Very low socio-economic status-Participant with no monthly income, Low socio-economic status-Participant with a monthly income less than 250 USD, Medium socio-economic status-Participant with a monthly income between 250 USD and 500 USD

Table 3

 3 Characteristics of Keys informants interviewed in the qualitative component, Côte d'Ivoire, 2019

	Characteristics	KI (1)	KI (2)	KI (3)	KI (4)	KI (5)	KI (6)
	Age (years)	48	44	59	36	45	49
	Gender	W	M	W	M	M	M
	Designation	Midwives	Oncologist	Midwives	Gyneacologist	Gyneacologist	Oncologist
	Working experience (years)	10	9	22	9	15	11

Notes: W-Women; M-Men; KI-Key Informant

Table 4

 4 Factors associated with advanced cervical cancer (FIGO stage: III or IV), Côte d'Ivoire, 2019, (n = 95)

	Cancer Stage at
	diagnosis
	Early	Advanced	Unadjusted OR	P value	Adjusted OR	P
	stage	stage (III/	(95% CI)		(95% CI)	value
	(I/II)	IV)

.007 Prior Knowledge of cervical cancer™

	Yes	19/51	32/51	1		1
	No	8/44	36/44	2.7 [1.0-6.9]	0.04	2.1 [0.7-6.3] 0.16*
	Use traditional healers©
	No	22/63	51/63	1
	Yes	5/32	27/32	2.9 [1.0-8.5]	0.05	-	-
	Access to specialized facilities¥
	Reference	25/76	51/76	1		1
	Directly	2/19	17/19	4.2 [0.9-19.4]	0.07	7.1 [1.1-44.0] 0.01
	Number of pre-diagnosis visits
	<3	9/33	24/33	1
	≥3	18/62	44/62	0.9 [0.3-2.3]	0.85
	Histological subtypes
	Adenocarcinoma	1/9	8/9	1
	Squamous cell carcinoma	26/86	60/86	0.3 [0.03-2.4]	0.25
	Total time interval®
	<180	10/40	30/40	1
	≥180	17/55	38/55	0.7 [0.3-1.8]	0.52
	Bold typeface indicates statistically significant values

*Confounding factor with HIV status and Health insurance coverage Notes: $, people who lived in other districts of Côte d'Ivoire except Abidjan; ™, Prior knowledge of CC before disease onset; ©, Use of traditionals healthworkers after recognition of early symptoms; ¥, How women get access to specialized facilities; ®, time between the first symptoms and the histological diagnosis of cancer.

Abbreviations: OR-Odds ratio; CI-Confidence Interval

Acknowledgements

We thank the National Cancer Control Program of Côte d'Ivoire which enabled us to obtain the necessary approvals to perform the study at public and private health facilities for cancer management in the urban area of Abidjan. We also thank all the participants who agreed to participate in this study. We want to acknowledge Marie Anicette Beda, Anicet Serge Edoukou, Guy Abele and Frank Kouassi for their involvement in this study. We Thank Prof. Roger Salamon for his considerable support in the accomplishment of this study.

Funding

Open Access funding enabled and organized by Projekt DEAL. The study was conducted under the IeDEA West Africa collaboration grants funded by the National Cancer Institute (NCI); Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD); National Institute of Allergy and Infectious Diseases (NIAID); Grant number: 5U01AI069919.

Authors' contributions MKP conceptualized, designed and implemented the study, collected data, performed data analysis/interpretation and drafted the manuscript. SB worked on study implementation, data collection and reviewed the manuscript. PC assisted data collection and analysis. AI, AH, AT and FD made the critical review of the manuscript for important intellectual content. AB assisted qualitative data collection/analysis and drafting of the manuscript. AJ supervised the study's conceptualization, design, implementation, data collection and analysis, also assisted drafting of the manuscript. All authors contributed to reviewed and approved the final version of the manuscript.

Data availability

The datasets generated and/or analyzed during the current study are not publicly available as they contain confidential information that could compromise privacy but can be made available with non-identifiable aspects from the corresponding author on reasonable request.

Declarations Ethics approval and consent to participate

The present study has been performed in accordance with the Declaration of Helsinki and has been approved by the National Ethics Committee of Côte d'Ivoire (approval number: 011-19/MSHP/CNESVS-kp). Informed consent to participate in the study and to do audio recording were obtained before each interview. For illiterate participants, informed consent was obtained from their legally authorized representatives. All the questionnaires, recorded tapes and transcripts were kept anonymous in the personal computer of the researchers which had a password. The study findings were reported anonymously.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

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