Associate Professor Amélie Clauzel
email: amelieclauzel@gmail.com

Hélène Delacour
email: helene.delacour@univ-lorraine.fr

Professor Sébastien Liarte
email: sebastien.liarte@univ-lorraine.fr

When cuisine becomes less haute: The impact of expert ratings on consumers' legitimacy judgments

Keywords: Legitimacy, neo-institutional theory, online review, consumers' judgment, expert ratings, gastronomy

What happens when expert ratings downgrade an organization? How does this downgrading influence the consumers legitimacy's judgments? To answer this issue, we study the 'Relais Bernard Loiseau' that was downgraded from a three-star to a two-star restaurant by the widely recognized expert, the Michelin Guide. Based on the quantitative and qualitative analysis of the 665 online reviews on the TripAdvisor website from 2004 to June 2017, our findings reveal a null effect on the rating (quantitative component of the evaluation) and a non-linear influence on their online comments (qualitative component). Our findings thus underline the great role of negative emotions in their judgement process, as the emergence of three positions towards the Michelin Guide that evolve: disapproval, approval and impartial. Those findings contribute to nourish the nascent bridge between neo-institutional theory and consumer-behavior field.

Introduction

In recent years, literature has increasingly recognized the key role of critics and experts, as well as the media, in shaping consumers' judgment in terms of experience goods (e.g. [START_REF] Durand | Code and conduct in French cuisine: Impact of code changes on external evaluations[END_REF][START_REF] Hsu | Jacks of all trades and masters of none: Audiences' reactions to spanning genres in feature film production[END_REF]. The guidance offered by experts, such as the Parker Guide for wine [START_REF] Humphreys | Status games: Market driving through Social Influence in the US Wine Industry[END_REF], the Grammy Awards for music [START_REF] Anand | Tournament rituals in the evolution of fields: The case of the Grammy Awards[END_REF]) and the Booker Prize for fiction writing (Kovàcs & Sharkey, 2014), plays a crucial role in shaping consumers' judgments and expectations [START_REF] Wang | Protecting market identity: When and how do organizations respond to consumers' devaluations[END_REF]. This influence has been mainly studied through the lens of positive expert evaluations, whereby an award or high-ranking position positively influences the success and sales of the good in question, as well as the perception of legitimacy by consumers [START_REF] Humphreys | Framing the game: Assessing the impact of cultural representations on consumer perceptions of legitimacy[END_REF]. Indeed, a positive evaluation from experts underlines and confirms an appropriateness to existing norms and standards (e.g. [START_REF] Rao | Institutional change in Toque Ville: Nouvelle cuisine as an identity movement in French gastronomy[END_REF] and, as a consequence, is considered a static reference that cannot easily evolve.

Within such a context, we may wonder what happens when a widely recognized expert downgrades an organization. Although rare and exceptional, such a downgrade can lead to a loss of legitimacy and influences consumers' judgment; a process currently overlooked by the existing research (e.g. d [START_REF] Astous | Consumer evaluations of movies on the basis of critics' judgments[END_REF]. Furthermore, the way in which consumers' complex reactions, not only rational but also emotional (Huy, Corley & Kratz, 2014), are triggered also warrants further investigation. Given the influence of expert judgments on experience goods, downgrading provides a great avenue through which to study its influence on consumers' judgment of legitimacy.

To explore this issue, we focus on the haute cuisine field, in which the Michelin Guide is acknowledged as the most influential of critics [START_REF] Durand | Code and conduct in French cuisine: Impact of code changes on external evaluations[END_REF][START_REF] Ferguson | Accounting for taste: The triumph of French cuisine[END_REF][START_REF] Gomez | The emergence of an influential practice: Food for thought[END_REF][START_REF] Karpik | Le Guide Rouge Michelin[END_REF][START_REF] Karpik | Valuing the unique: The economics of singularities[END_REF]. Despite its extremely conservative behavior and stable evaluation criteria [START_REF] Durand | Code and conduct in French cuisine: Impact of code changes on external evaluations[END_REF], February 2016 saw the Michelin Guide downgrade the 'Relais Bernard Loiseau' -a French gourmet restaurant located in Burgundy (eastern France) -from a three-star (the highest ranking) to a two-star establishment. Such a downgrade is rare; since its creation in 1934, the Michelin Guide has only downgraded 19 three-star French restaurants. The guide has always remained silent as to its reasons why [START_REF] Rao | Institutional change in Toque Ville: Nouvelle cuisine as an identity movement in French gastronomy[END_REF].

Acting as a professional certification [START_REF] Ferguson | Accounting for taste: The triumph of French cuisine[END_REF], Michelin stars represent a commonly accepted proxy of legitimacy [START_REF] Rao | Institutional change in Toque Ville: Nouvelle cuisine as an identity movement in French gastronomy[END_REF]. As such, downgrading represents not only a loss of legitimacy for the restaurant but could also influence consumers' judgement, since stars represent the most valued criterion for all agents in the field [START_REF] Karpik | Le Guide Rouge Michelin[END_REF][START_REF] Gomez | The emergence of an influential practice: Food for thought[END_REF]. In this context, we seek to explore how a negative evaluation, made by an expert, influences consumers' judgment on legitimacy.

To do this, we analyze the 665 online reviews of the 'Relais Bernard Loiseau' posted by the consumers on the TripAdvisor website, from 2004 to June 2017, through a mixed method based on quantitative data (regression and analysis of variance) and qualitative data (correspondence analysis, automatic textual analysis and content analysis).

Our findings reveal a null effect on the rating assessed by consumers and a non-linear influence on the online comments that evolve between the short and long term with the emergence of new criteria of evaluation, combined to a great confusion between them, an increase and then decrease of negative emotions. Finally, we observe the emergence of three positions of consumers towards the Michelin Guide that evolve and influence their judgement: disapproval, approval and impartial.

Those findings allow us to contribute to the literature on legitimacy judgment in revealing the complex relationship between negative expert judgement and consumers' one, underlining the great role of negative emotions in the consumers' judgment, and nourishing thus the nascent bridge between neo-institutional theory and consumer-behavior field.

Theoretical background

The different audiences of legitimation

Legitimacy is defined as "the perceived appropriateness of an organization to a social system in terms of rules, values, norms and definitions" (Deephouse et al., 2017, p. 36), highlighting thus a strong perceptional component. Following this conceptualization, literature acknowledges that legitimacy can be granted by a variety of audiences, such as media [START_REF] Deephouse | Does isomorphism legitimate?[END_REF][START_REF] Humphreys | Framing the game: Assessing the impact of cultural representations on consumer perceptions of legitimacy[END_REF], State, regulators, experts but also recently individuals such as consumers (Suddaby, Bitekine & Haack, 2017;[START_REF] Tost | An integrative model of legitimacy judgment[END_REF]. Each audience, whether consciously or not, use different set of cognitive processes (Bitketine, 2011;[START_REF] Tost | An integrative model of legitimacy judgment[END_REF], different criteria or standards (Ruef & Scott, 1998) for evaluating organizations and communicating their evaluations and perceptions to others. Depending on the industry to which an organization belongs, all the audiences are not equivalent. For example, artists are evaluated by both museums and art galleries [START_REF] Ertug | The art of representation: How audience-specific reputations affect success in the contemporary art field[END_REF]. In the case of the haute cuisine field, the case under consideration, research reveal the role of two key audiences [START_REF] Karpik | Le Guide Rouge Michelin[END_REF] in assessing legitimacy: critic considered expert and consumers, i.e. individuals. As legitimacy is a socially constructed perception, the way these different audiences interact each other starts to be examined [START_REF] Bitekine | Toward a theory of social judgments of organizations: The case of legitimacy, reputation, and status[END_REF][START_REF] Tost | An integrative model of legitimacy judgment[END_REF]. We follow this perspective by exploring the influence of a negative evaluation made by an expert audience on the legitimacy judgment made by the consumer audience.

The influence of expert judgement on consumers' judgement

For some industries and experience goods, such as financial markets, healthcare, sports, movies, book, restaurants, wine or gambling, the influence of critics, experts, or media are critical for consumers (Hadj Ali, Lecoq & Visser, 2008;[START_REF] Durand | Code and conduct in French cuisine: Impact of code changes on external evaluations[END_REF][START_REF] Humphreys | Status games: Market driving through Social Influence in the US Wine Industry[END_REF][START_REF] Humphreys | Framing the game: Assessing the impact of cultural representations on consumer perceptions of legitimacy[END_REF][START_REF] Kovács | The paradox of publicity: How awards can negatively affect the evaluation of quality[END_REF][START_REF] Reinstein | The influence of expert reviews on consumer demand for experience goods: A case study of movie critics[END_REF], who rely on such evaluations when considering whether a product, service or organization is legitimate [START_REF] Hsu | Jacks of all trades and masters of none: Audiences' reactions to spanning genres in feature film production[END_REF]. This influence has been mainly explained by the uncertainty faced by consumers. "When the experience is highly ambiguous, consumers struggle to develop an independent and objective evaluation" (Humphreys & Carpenter, 2018, p. 150). In such context, experts contribute to "dissipate the opacity of the market […] [and] reduce the cognitive deficit that characterizes consumers" (Karpik, 2010, p. 44). In evaluating first, they provide some guidance to consumers' judgement [START_REF] Durand | Code and conduct in French cuisine: Impact of code changes on external evaluations[END_REF] and shape their expectations [START_REF] Wang | Protecting market identity: When and how do organizations respond to consumers' devaluations[END_REF].

This guidance is all the more important when one considers that critics and experts refer to stable criteria, i.e. the conformity to norms and standards to assess the value of a product or service [START_REF] Rao | Institutional change in Toque Ville: Nouvelle cuisine as an identity movement in French gastronomy[END_REF], and in doing so provide a static reference.

The influence of a negative expert judgment on consumers' legitimacy judgment

An even rarer instance is when, after awarding an organization, a wine, a movie, a book, experts decide to downgrade it through negative evaluations (e.g. d [START_REF] Astous | Consumer evaluations of movies on the basis of critics' judgments[END_REF].

What happens in such a case? If consumers are mostly influenced by the value of experts' opinions [START_REF] Holbrook | Popular appeal versus expert judgments of motion pictures[END_REF], what relationships can we expect between experts' and consumers' judgments on the legitimacy of an organization? We face a paucity of research regarding the influence of a negative expert judgment on that of consumers. However this is an important issue as if scholars have stressed the importance of expert as a source of validity cues [START_REF] Bitekine | The macro and the micro of legitimacy: Towards a multilevel theory of the legitimacy process[END_REF] to assess the legitimacy of an organization for consumers, recent research tend to consider consumers no more as a passive audience but rather as an active one. Following this perspective, [START_REF] Tost | An integrative model of legitimacy judgment[END_REF] suggests that, when legitimacy is contested, consumers are willing to engage more in the process of legitimacy judgment. Furthermore, consumers' reactions are not just rational but emotional [START_REF] Huy | From support to mutiny: Shifting legitimacy judgments and emotional reactions impacting the implementation of radical change[END_REF]; a distinction that could influence their perception. This echoes a recent call in neo-institutional research as we know very little about how consumers use emotions and feelings in evaluating organizations [START_REF] Deephouse | Organizational legitimacy: Six key questions[END_REF] and more generally the role of emotions in legitimacy judgment [START_REF] Lok | Living institutions: Bringing emotions into organizational institutionalism[END_REF][START_REF] Voronov | Integrating emotions into the analysis of institutional work[END_REF], which can be addressed not only through the organization under consideration but also the expert who expresses the negative judgment.

To explore the issue of how a negative expert rating influences consumers' legitimacy judgment, we consider the case of the 'Relais Bernard Loiseau' restaurant in the haute cuisine field.

Context and methods

Research context

The 'Relais Bernard Loiseau' belongs to the highly institutionalized field of haute cuisine [START_REF] Ferguson | Accounting for taste: The triumph of French cuisine[END_REF][START_REF] Gomez | The emergence of an influential practice: Food for thought[END_REF]. In 1977, two years after opening his own restaurant in Saulieu (a small town in Burgundy), Bernard Loiseau received his first star from the famous and widely recognized expert, Michelin Guide [START_REF] Karpik | Le Guide Rouge Michelin[END_REF]. This young chef became famous for his own style of refined cuisine, with a number of signature dishes. In 1991, he gained his third star, the consecration of the Michelin Guide. Indeed, the Michelin Guide confers a maximum of three stars to restaurants worth a special journey [START_REF] Karpik | Le Guide Rouge Michelin[END_REF].

In 2018, only 28 restaurants in France were awarded three-star, i.e. 4% of restaurants ranked.

For 25 years, the three stars remained stable, despite the death of Bernard Loiseau in February 2003. After his death, his wife, Dominique Loiseau, took over as head of the Relais and the sous-chef, Patrick Bertron who had worked for more than 20 years with Bernard Loiseau, became the new chef of cuisine.

In February 2016, the Michelin Guide downgrades it from a three-star to a two-star restaurant, representing a loss of legitimacy. We seek to explore the influence of this negative expert judgment on the consumers' one, through the TripAdvisor website that allows consumers to rate and evaluate an organization [START_REF] Karpik | Valuing the unique: The economics of singularities[END_REF][START_REF] Lamont | Toward a comparative sociology of valuation and evaluation[END_REF]. We thus could observe this influence on the rating (quantitative component of their evaluation) but also the online comments (qualitative component) made by consumers. This qualitative component allows us to account for not only the potential role of emotions in consumers' legitimacy judgment towards the organization, but also the other audience who assesses legitimacy: the Michelin Guide.

Data collection

Exploring our issue requires an empirical setting in which consumers' perceptions are available for a long period to study their potential evolution between before and after the expert negative judgment. As the most commonly used by consumers in Europe and in France in particular [START_REF] Ayeh | Do we believe in TripAdvisor?" Examining credibility perceptions and online travelers' attitude toward using user-generated content[END_REF]Zaman, Botti & Thanh, 2016), the TripAdvisor platform meets our requirements and allows to collect rich qualitative and quantitative data, which are both spontaneous and independent (e.g., Zaman et al., 2016).

On this platform, consumer reviews are based on an algorithm and a form designed by TripAdvisor, including an overall five-items scale rating and ratings of different components of experience: quality-price ratio, location, cleanliness and service, as well as textual comments and photos. TripAdvisor encourages consumers to report on their experience by writing a free textual comment. Additional and optional information about consumers is also available, such as age, gender, geographical origin, number of emitted posts, date of issue and date of stay.

Our dataset represents all the 665 online reviews posted on this website since the first publication in August 2004. As all reviews provide ratings and online comments (data analyzed), we collected all of them. We ended our data collection in June 2017 with the launch of a new menu, and a new adapted pricing scheme. As 70% of the online reviews come from French consumers, we first used the translation service of the TripAdvisor website for the 30% of comments written in foreign languages, as such translations are the ones read by French consumers. We then submitted these automatic translations to a copyeditor, with the original text, to ensure their quality and robustness and to make change when necessary (exceptions include specific languages such a Russian, Chinese or Japanese, which represent less than 5% of all comments).

To improve the validity of our analysis, we also conducted ten semi-structured interviews.

These consumers were chosen according to their age, sex, gourmet restaurants and 'Relais Bernard Loiseau' visit frequencies (Table 1). The interview guide is mainly based on the perception of this loss of the third star, the way they reacted at that time and their current evaluation.

- ------------------------------Insert Table 1 about here - -------------------------------To have a deeper understanding of the context, we collected complementary data, such as newspaper articles, relating to the loss of the third star, visited the 'Relais Bernard Loiseau', and interviewed four employees: Dominique Loiseau, the head of the 'Relais', Patrick Bertron, the chef, and two persons in charge of communication.

Data analysis

We adopted a mixed method based on quantitative data (regression and ANOVA) and qualitative data (correspondence analysis, automatic textual and content analysis). Before analyzing our data, we splitted them into three distinct periods, labelled 'Before', 'After 1' and 'After 2'. The 'Before' period, where the restaurant was a three-star, spans from August 2004 to January 2016 (420 online reviews). After the loss of the third star, we considered two separated periods to study evolutions on a short and a longer term. The 'After 1' period takes into account the immediate reactions and lasts six months, from February to July 2016 (88 online reviews), as in this type of restaurant, consumers generally book several months in advance. The 'After 2' period lasts from August 2016 to June 2017 (157 online reviews), date of a new menu and pricing scheme.

We followed four steps of analysis.

First, we explored the influence of this negative expert judgment on the rating through two analyzes (quantitative data). To explain the global rating and, particularly, which factors (among the four items initially evaluated by consumers on TripAdvisor) contribute the most, a multinomial logistic regression was first conducted (Appendix 1). This led us to keep three items (quality-price ratio, cleanliness and service) for the ANOVA (Table 2).

We then performed a content analysis of the comments (qualitative data), through different steps. In the second step, to observe the potential evolution of criteria on which consumers assess the restaurant, we used a correspondence analysis via a descendent hierarchical classification for each period. The aim of the algorithm is to order the textual data source through a process of categorization and reduction. The complete textual corpus is divided into different word classes "that simplify it while maximizing the structure of the text" (Daudigeos Boutinot & Jaumier, 2013, p. 331). The different classes of words selected maximize the deviation from a uniform distribution of words (measured by a Chi-square). As underlined by Daudigeos et al. (2013, p. 331), "[a] deviation from the uniform distribution may signal the intention of the author of the discourse to associate words in a special manner in order to create meaning". Once built by the algorithm, we labelled, for each period, the different classes in accordance with the words they contain, i.e. criteria of evaluation.

In order to visualize their structure and patterns, a correspondence analysis was conducted. By scaling the rows and columns of the rectangular data matrix obtained by the descendant hierarchical classification in corresponding units, factorial analysis allows to plot the scores of the most significant words in the same space for ease of interpretation [START_REF] Hoffman | Correspondence analysis: Graphical representation of categorical data in marketing research[END_REF]. It was then possible to interpret the distance in space between words (and by extension between classes of words). To do so, we used a qualitative module, IRAMUTEQ, of R platform (step 2).

In the third step, we attempted to reveal the potential evolution of the emotions contained in consumers' comments. To achieve it, we used a text-analysis software, Linguistic Inquiry and Word Count (LIWC), to categorize multiple dimensions of language [START_REF] Humphreys | Automated text analysis for consumer research[END_REF][START_REF] Wang | Protecting market identity: When and how do organizations respond to consumers' devaluations[END_REF]. LIWC searches, counts and codes words according to its own dictionary. Among the 80 categories available, related to our research question, we considered the following ones: anger, sadness, negative emotion, causation, tentative, inhibition and assent. LIWC program calculates the percentage of total words contained in each comment that match with those categories. A mean of percentage of total words based on all the comments contained in a period was calculated to analyze the possible evolution along the three periods. Non-parametric Mann-Whitney tests were performed in pairs between the three periods (Step 3).

In the fourth step, to deep our analysis on the influence between expert and consumers' judgement, we selected a sub-sample that mentioned the words related to 'star' (star, stars, starred) and 'Michelin' (Guide, Michelin) after the loss of the third star, i.e. online comments that directly refers to the Michelin Guide and its judgment. This sub-sample represents 52 online comments (22 for 'After 1' and 30 for 'After 2') among the 245. Following an inductive perspective, two of the authors coded separately this sample, confronted their results until an agreement of about 90% among them was reached. As suggested by [START_REF] Strauss | Basics of qualitative research[END_REF], we had pre-existing categories in mind but were open to other categories that might emerge from the data. Coding led us to identify three aggregated positions of consumers towards the Guide: disapproval, approval and impartial (Step 4). To support these three last steps, we cross-checked our results with those of the ten semi-structured interviews.

Results

Step 1: Influence on the rating of consumers' judgement

Our results indicate that the loss of the third star has a null effect on the evaluations of consumers who quantitatively assess the restaurant at the same level. As specified in Appendix 1, the global significant multinomial logistic regression (p=0,013) carried out to explain the global rating indicates that this item is explained by, first, the cleanliness (p=0.000); second, by the quality-price ratio (p=0.000); and third, by the service (p=0.000).

The location score was dropped from the ANOVA as it has no significant impact on the global rating.

The ANOVA analysis indicates that the cleanliness and quality-price ratio items are unaffected by the loss of the third star; their respective averages are not statistically different (Table 2). Concerning the service item, its devaluation can be explained by the nuisances caused by the expansion works for the construction of a huge spa (more than 1,500 square meters) beside the restaurant during this period: "First of all, the building extension, which offers a view of a rotating crane […] The dinner was very good but the place was dusty" (Emmanuel95, 27 February 2016) or "The view was ruined by a huge crane [...] Mrs. Loiseau had a large complex built adjacent to the hotel... Business acumen is good, hospitality is better!" (Mnemo75, May 2015).

- ------------------------------Insert Table 2 about here --------------------------------These results indicate that the expert negative judgment does not influence the global mean rating of consumers, nor the evaluation of other peripheral items (except for service). Since the rating as a metric variable (quantitative component of evaluation) is complex to interpret on its own, we completed our analysis by taking into consideration the online comments (the qualitative component), through different steps.

Step 2: Influence on the criteria of consumers' judgment

To analyze the influence on the content of online comments, we first identified the evolution of clusters, i.e. criteria of evaluation, through a correspondence analysis based on a descendent hierarchical classification for each period identified.

Considering the 'Before' period, we observed four initial clusters: hotel (in red), i.e., the physical environment (room, garden, swimming pool, bath, bed, etc.); the general atmosphere of the place (in green) with words such as Bernard Loiseau's spirit, magical moment, excellent stay, sublime, mythical; hospitality and front-line employees (in blue) illustrated by hospitality, kindness, excellence, team or host, etc. and the restaurant (in purple) with words such as wine, food, price, restaurant, etc. As words of the first and second cluster are intrinsically intertwined, we merged them as one, under the label, 'atmosphere'. Fig. 1 spatially represents the three main clusters through a factorial analysis.

- ------------------------------Insert Figure 1 about here --------------------------------We observed that the second and third clusters are very close in terms of meaning and are clearly separated from the other two. In short, consumers evaluate the physical environment (hotel), the restaurant (elementary or basic service) and the general atmosphere of the place:

"Very high quality gastronomy and a stay in a chic rustic setting. 'Le Relais Bernard Loiseau' is an embassy of the French way of life" (Johannès, 3 May 2010).

Considering the period just after the loss of the third star, 'After 1', we observed the emergence of a new criteria, labelled reputation (reputation, explanation, excellence, note, French, quality, etc.), and the growing closeness between other clusters. Fig. 2 illustrates that if the two clusters (hotel and restaurant) are still distinct, both are intertwined with that of atmosphere, which becomes central. These trends suggest that the loss of the third star directly introduces a less clear structure in consumers' judgment.

- ------------------------------Insert Figure 2 about here --------------------------------Indeed, the atmosphere's criteria previously had two sub-dimensions that were previously expressed separately: one related to the general atmosphere of the place and another related to hospitality and front-line employees. After the loss of the star, a new sub-dimension emerges, the reputation and is categorically intertwined with the two others. "The hotel and catering service is up to the reputation of the great houses […] "However, it's unfortunate that the reputation of an establishment does not come from those paying the bill, but from a company with zero connection to the place in question." (François M., 20 April 2016). This increases confusion between the three sub-dimensions and reveals the difficulty that consumers have in reaching a clear judgment with distinct criteria. Furthermore, within the criteria, we note an evolution of the terms used. For example, the restaurant's cluster includes new terms, such as the name of the chef, Patrick Bertron, which is introduced for the first time: "[…] To complete this beautiful evening, we were offered to visit the kitchen once the shot is over. Of course, we accepted: the chef himself (Patrick Bertron) who takes the time to talk about his passion" (Petitsgourmands78100, 28 February 2016). The loss of the star is also discussed by consumers: "Although everything has probably already been said, the question remains: how and why did this beautiful place lose its third star?" (Pastis04, 21 April 2016).

During the third period ('After 2'), i.e., from six months after the loss of the third star to June 2017, the analysis reveals that the hotel cluster and that of atmosphere get closer.

Interestingly, proximity between the two grows in line with confusion, in that consumers become increasingly prone to introducing different criteria to their evaluations. This can also be explained by the emergence of a new cluster about price. A price reduction is expected by consumers: "This restaurant is very good, but does not reach the level of excellence of other great French restaurant. However, the menu price is at the same level" (Lofteur, 24 August 2016) or "I do not know about this star loss […] But it may be necessary to revise their prices" (Maril, 10 May 2017). This creates increased confusion between all the dimensions related to the atmosphere (Fig 3).

-------------------------------Insert Figure 3 about here --------------------------------However, our results indicate that the restaurant cluster is still distinct from the others.

Contrary to the previous periods, consumers provide more detailed descriptions of the different dishes or quality: " The poached foie gras with artichoke puree is very well cooked and the harmony of the flavors is successful […] the snails in tempura are not at all at the level of what can be expected in a gourmet restaurant" (Mamuguiphi, 26 September 2016).

Consumers use technical language in an apparent attempt to be seen as informed with a real expertise in the haute cuisine.

To conclude, we observe that the loss of the third star influences the content of the online comments through the emergence of new criteria (reputation first, and then price) (Table 3 for illustrative quotes) and the increase confusion between them. If the restaurant' criteria still stays distinct from the others, we note an evolution in the terms used as a way to be more engaged in their judgment and legitimate them. To explore this potential stronger involvement in a context which appeals to consumers' emotions, we perform a LIWC analysis.

- ------------------------------Insert Table 3 about here - -------------------------------

Step 3: Influence on the emotional content of the online comments

The results of LIWC analysis (Table 4) indicate a significant increase of words related to negative emotions immediately after the loss of the third star (+28.7% between 'Before' and 'After 1').

- ------------------------------Insert Table 4 about here --------------------------------This result is consistent with previous research highlighting that negative emotion words are used in writing about a negative event [START_REF] Kahn | Measuring emotional expression with the Linguistic Inquiry and Word Count[END_REF] among which a loss of legitimacy (Huy et al., 2004). As illustrated by Peter (Interview 6): "I didn't expect it. But just I said to myself, it's a shame now that they lost that star they'll never find it". In detailing words related to negative emotions, they encompass significantly more anger (+66.7%) and sadness (+22,5%). This increase reflects a stronger involvement from consumers in the process of legitimacy judgement, as theoretically suggested by [START_REF] Tost | An integrative model of legitimacy judgment[END_REF]. However, the use of negative emotion words significantly decreases in the long term and are closed to those before the loss (0.831 for 'Before' vs. 0.873 for 'After 2'). This result echoes literature on surprise effect [START_REF] Bagozzi | The role of emotions in marketing[END_REF] underlining that the influence is stronger in the six months following a negative surprise [START_REF] Ford | Finding the good in the bad: Age and event experience relate to the focus on positive aspects of a negative event[END_REF].

In parallel, we observed a significant increase of causal words between the periods 'Before' and 'After1' (+39.6%), suggesting the willingness of consumers to justify their judgment [START_REF] Tost | An integrative model of legitimacy judgment[END_REF]. But at the same time, they seem less confident as revealed by the increase of tentative words (+12.7%): "Coming with a priori following the Michelin Guide, we had a wonderful moment […] It is probably not the most creative cuisine, nor the most stylish hotel […] If I had to find a downside" (Denis, 5 March 2016). We observe an influence of the expert negative judgment on the content of consumers' judgment, through an increase of their negative emotions and the introduction of doubts in their evaluations. This result is consistent with the observation of a less clear structure of their judgment in step 2.

Finally, the decrease of assents words measuring the level of agreement (-33%), related to the increase of negative emotions (+28.7%) reveals a disagreement between consumers and the expert' judgement in a short term ('After 1). In a longer term ('After 2'), the increase of assent words (+60.7%) reveals rather a consensus. However, this consensus may be considered as not totally an in-depth coping strategy [START_REF] Duhachek | Coping: A multidimensional, hierarchical framework of responses to stressful consumption episodes[END_REF] due to the important increase of words related to inhibition (+46.8%) but rather as a surface coping strategies [START_REF] Hur | The moderating role of perceived organizational support on the relationship between emotional labor and job-related outcomes[END_REF] as illustrated by Valerie (Interview 1): "Disappointed but also a little questioning. If professionals have said it was less suitable for a 3-star rating, they may also be right".

To deepen our analysis of emotional content and further our analysis of the assent dimension in the relationship between expert and consumers, we perform a content analysis.

Step 4: Influence of the Michelin Guide on the online comments

The qualitative analysis of the 52 online comments (22 for 'After 1' and 30 for 'After 2') that directly mention the words 'star' and/or 'Michelin' after the loss of the third star reveals that this downgrading is differently perceived by consumers. Three positions towards the Michelin Guide were observed: disapproval, approval and impartial, with an evolution of proportion and content.

In the short term ('After 1'), a majority of consumers (55% of this subsample) express a disapproval towards the Guide. Consumers refer to negative emotions to express their disapproval and question the expert judgment. As they find this negative judgment unjustified, they choose to actively support the restaurant: "Excellent. I do not understand why this restaurant lost a star" (Marie-Pierre, 7 June 2016). The content analysis reveals the use of several arguments to justify their disapproval, underlining a strong involvement in their legitimacy judgment, while, at the same time, leaving room for doubt. These observations are consistent with those observed through LIWC analysis with the increase of causation (+39.6%) and tentative (12.7%) words in the period 'After1'. On the contrary, 30% of consumers approve expert judgment in supporting directly the apparently deserved loss of the third star: "I understand the loss of the third star. We are far enough from a three-star" (Kharrin, 5 July 2016). Finally, 15% of the online comments evoke the loss of the star in an impartial way: "Thank you to the entire Bernard Loiseau' team for this exceptional stay. Two or three stars, who cares?" (Laurent, 8 March, 2016).

In a longer term ('After 2'), we observe two evolutions. First, if the proportion of disapproval (38.3%) and approval (29.8%) towards the Guide decreases, the content of their comments evolves, leading to a more radical opposition between them and the use of particularly strong negative terms: "How the Michelin Guide could remove a star from this place and keep three stars at the Paul Bocuse restaurant, which is completely outdated!" (Misnard, 27 March 2017) vs. "a really mediocre experience and, for us, not up to the height of its stars and reputation" (Nickoparis, 11 October 2016). Among consumers remain impartial towards the Guide, they go even further and mention the possibility of losing the second star: "For a twostar Michelin restaurant, the dinner, compared to other star restaurants frequented, is not, in my opinion, as good as these stars!" (Rassian, 2 October 2016).

Second and in relation to, the proportion of impartial position increases (31.9%). This observation is in line with the positive evolution of assent words (+60.7%) between the periods 'After 1' and 'After 2'. This increase of impartial comments can be explained by the fact that the restaurant is more often evaluated as a two-star with less reference to the loss of the third star: "A chef who absolutely deserves these 2 stars" (Veronique, 28 May 2017). Some comments even do not refer to a number of stars but just evoke a restaurant "with Michelin stars": "Super gastro restaurant. It deserves its stars" (Vanillevodka, 30 April 2017). By evaluating in a lower (two-star restaurant) or in a broader ("star restaurant") manner, an impartial position towards the Guide appears easier to adopt.

Discussion and conclusion

In this article, we explore the influence of a negative expert judgment on consumers' legitimacy judgment. To do so, we studied the evolution of the legitimacy judgement towards the 'Relais Bernard Loiseau' by consumers following its downgrading from a three-star to a two-star restaurant in February 2016 by the expert Michelin Guide. Our analysis of the online reviews posted by consumers on the widely used TripAdvisor website reveal a null effect on the rating (quantitative component of the evaluation) and a non-linear influence on their online comments (qualitative component). Contrary to research that underline a direct and positive influence of expert judgment on consumers' one (e.g. [START_REF] Humphreys | Framing the game: Assessing the impact of cultural representations on consumer perceptions of legitimacy[END_REF], our findings reveal that in a case of a negative expert judgement, this influence does not follow the same pattern. Our results led us to contribute to the nascent bridge between neo-institutional theory and consumers behavior field [START_REF] Chaney | A neo-institutional analytic grid for extending marketing to institutional dimensions[END_REF] in several ways.

First, contrary to research suggesting that a bias of conformity can be applied and that consumers will follow the expert judgement [START_REF] Holbrook | Popular appeal versus expert judgments of motion pictures[END_REF][START_REF] Hadj Ali | The impact of gurus : Parker Grades and en primeur wine prices[END_REF], especially when the taste and the subjectivity are important, our findings reveal a null effect on the rating. Despite primarily surprising, this null effect can be explained technically by the 5-point scale [START_REF] Peterson | Measuring customer satisfaction: Fact and artifact[END_REF] developed by TripAdvisor that limits consumers' ability to adjust their rating unless really sanctioning the restaurant. As underlined by Eric T.

(2 April 2007): "The problem of the rating system is that there is no intermediary position between average and very good. It wasn't average, and it wasn't very good -it was good, no more and no less." Furthermore, by conformity to the norms and standards (reference to the normative legitimacy), a gourmet restaurant is still well ranked on the TripAdvisor website, whether its number of stars, with a rating between 4 and 5, reflecting a rapid simplifying process for transforming qualities into quantities [START_REF] Espeland | Rankings and reactivity: How public measures recreate social worlds[END_REF]. This null effect on the rating tends to nuance its role on the legitimacy judgment, for the benefit of the online comments as suggested by two complementary streams of literature. On the one hand, considering the rating as the outcome of the legitimacy judgement process, and the comments as the process [START_REF] Tost | An integrative model of legitimacy judgment[END_REF], our findings suggest to more focus on the process to explain the outcome of this legitimacy judgement [START_REF] Bitekine | Toward a theory of social judgments of organizations: The case of legitimacy, reputation, and status[END_REF][START_REF] Bitekine | The macro and the micro of legitimacy: Towards a multilevel theory of the legitimacy process[END_REF] as an apparent lack of change of the outcome can be supported by major evolutions in terms of process. On the other hand, recent research in marketing underline the role of the online comments as a fundamental narrative compensation for online reviews [START_REF] Liu | What makes a useful online review? Implication for travel product websites[END_REF].

The narrative details could even have an even more significant influence on other consumers than just the rating score [START_REF] Van Laer | What happens in Vegas stays on TripAdvisor? A theory and technique to understand narrativity in consumer reviews[END_REF]. Thus, our findings suggest to no limit the study on the rating that could be difficult to interpret alone but also to encompass the in-depth analysis of the comments to fully understand the influence on consumers' judgement.

Second, in addition to being indirect, this influence is non-linear in relation to the evolution of online comments over time. Indeed, we observe an increase confusion with the emergence and multiplicity of criteria that become difficult to differentiate, and in parallel an increase of negative emotions that tend to decrease in the long term with more and more consumers that tend to be neutral. Our results refine thus the central role of emotions in the post-consumption stage of the decision-making process, stage that has been less studied [START_REF] Bagozzi | The role of emotions in marketing[END_REF], and in experiential marketing, particularly in the luxury and creative fields [START_REF] Kim | Customer emotions and their triggers in luxury retail: Understanding the effects of customer emotions before and after entering a luxury shop[END_REF].

The loss of the third star can be assimilated to an unexpected shock that leads to too dissonant negative tensions that consumers have to deal with. If the negative emotions tend to decrease on the long term whatever the consumer, completing thus the work of [START_REF] Ford | Finding the good in the bad: Age and event experience relate to the focus on positive aspects of a negative event[END_REF], the progressive neutral position towards the Michelin Guide, and thus an increase consonance, cannot be considered an in-depth coping strategy [START_REF] Duhachek | Coping: A multidimensional, hierarchical framework of responses to stressful consumption episodes[END_REF] and deserves further research. This central role of emotions echoes also a recent trend in the literature of legitimacy judgment [START_REF] Lok | Living institutions: Bringing emotions into organizational institutionalism[END_REF][START_REF] Voronov | Integrating emotions into the analysis of institutional work[END_REF] in revealing empirically two types of negative emotions: anger and sadness. Our findings also suggest that these emotions alter their legitimacy judgement process with an increase of confusion and doubt. Furthermore, these negative emotions are addressed not to one but two distinct audiences: the organization but also the expert at the origin of the negative judgment. Disappointed consumers are more engaged to justify their judgement to support the organization whose legitimacy is contested. They can be considered active audience in assessing the organizational legitimacy [START_REF] Bitekine | The macro and the micro of legitimacy: Towards a multilevel theory of the legitimacy process[END_REF][START_REF] Tost | An integrative model of legitimacy judgment[END_REF], audience that has been left aside in neo-institutional literature [START_REF] Chaney | A neo-institutional analytic grid for extending marketing to institutional dimensions[END_REF]. Third, our results contribute to the relation of power between these two external audiences who confer legitimacy to an organization [START_REF] Orlikowski | What happens when evaluation goes online? Exploring apparatuses of valuation in the travel sector[END_REF]: expert vs. consumers.

Traditionally experts such as the Michelin Guide, the Booker Prize or the Grammy Awards represent the standard of continuity and act as a coordination mechanism in a field [START_REF] Karpik | Le Guide Rouge Michelin[END_REF][START_REF] Karpik | Valuing the unique: The economics of singularities[END_REF]. Today, they seem challenged by online-reviews platforms that, by compiling consumers' judgment, progressively exert influence [START_REF] Wang | Protecting market identity: When and how do organizations respond to consumers' devaluations[END_REF] and can be considered 'expert system' [START_REF] Jeacle | In TripAdvisor we trust: Rankings, calculative regimes and abstract systems[END_REF]. In this complex relationship between the expert audience which values tradition of continuity in evaluating a product or service a few times a year and a consumer audience that makes evaluation every day, this questions the legitimation dynamics, i.e. the sub-process of negotiation over who is a legitimate judge [START_REF] Lamont | Toward a comparative sociology of valuation and evaluation[END_REF]. Our findings suggest that in parallel to the expert audience, consumers become key audiences in the legitimacy judgment with increasing power [START_REF] Humphreys | Semiotic structure and the legitimation of consumption practices: The case of casino gambling[END_REF], as is the case of the 'Consumer Reports', which exerts great influence in how consumers choose their cars, for example. However, this dyad between expert and consumers should not overshadow the role the organization itself can play in this dynamic. Following a marketdriven approach, an organization can influence these both external audiences and be actively part of the legitimation process as suggested by [START_REF] Dion | Managing status: how luxury brands shape class subjectivities in the service encounter[END_REF] or [START_REF] Humphreys | Status games: Market driving through Social Influence in the US Wine Industry[END_REF].

These theoretical contributions have practical implications for both the organization and the expert. For the organization, beyond rethinking the role of the community manager from a defensive perspective, a strong presence on social networks and online platforms could reduce the influence of the expert's judgment. Transparent communication regarding the adaptation of certain offers following a downgrading could also be useful. To gain legitimacy, the community manager should offer systematic responses as suggested by [START_REF] Beuscart | Reactivity without legitimacy? Online consumer reviews in the restaurant industry[END_REF].

Following the market-driven approach, an organization may choose to focus on a particular audience and not the other. For example, chef Bras of the famous three-star restaurant 'Le Suquet', officially requested to not appear in the 2018 Michelin Guide. For the experts, they could consider integrating consumers' judgments into their marketing strategy, as seen in the famous Rotten Tomatoes website, which provides the movie judgments of both experts and consumers on the same web page. Doing so would increase the visibility for consumers, enhance the authority of experts, and deal with the observed empowerment phenomenon of online communities.

Finally, several limitations of our study provide promising opportunities for further research.

First, despite we focus on the restaurant 'Relais' cluster, online comments occasionally mention the hotel or the experience as a whole. This represents an inherent limitation, which has been nevertheless reduced when interviewing the organization members and ten consumers and by the fact that in the correspondence analysis, this cluster still remains distinct from the other criteria in the online comments. Second, despite we observed that the profile variables of consumers have no direct effect on the global rating (reviewer's gender: p=0.585, issuer's age: p=0.681; reviewer's geographical origin (French or not): p=0.741), it could be interesting to take into consideration the status of consumers, and notably the distinction between French and foreign consumers, in the way they perceive the legitimacy of this restaurant. Another limitation relies on the use of a unique website, TripAdvisor. Despite we collected all the online reviews available on this website and conducted ten interviews to limit sampling bias, a research perspective could consist in collecting data on other foodspecialized websites. However, these platforms are less widely used: lafourchette.fr (127 online reviews for the 'Relais') and Yelp.fr (13). To enhance our external validity, it could be useful to replicate our study for the other few restaurants that faced a loss of a third star.

Another way could be to apply this methodology in others luxury consumption contexts where excellence rewards are central such as the haute couture' label or finest jewellery.

  Zaman, M.,Botti, L., & Thanh, T. V. (2016). Weight of criteria in hotel selection: An empirical illustration based on TripAdvisor criteria. European Journal of TourismResearch, 13,[132][133][134][135][136][137][138]

Fig 1 .Fig 3 .

 13 Fig 1. Emergence of criteria in online comments before the loss of the third star (''Before'')

Table 3

 3 Illustrative quotes of the different criteria by consumers

Table 4

 4 The most emotive and cognitive LIWC dimensions

Categories from LIWC Average mean of % of words of a category

		Evolution in % and Mann-Whitney U tests
		August 2004 -	February 2016 -	August 2016
		January 2016	July 2016	-June 2017
		(Before)	(After 1)	(After 2)
	Negative emotions (hate, worthless, enemy, etc.)	0.873	+28.7% p=0.001	1.124	-26.1% p=0.000	0.831
			+66.7%		-32.3%
	Anger	0.186	p=0.000	0.310	p=0.000	0.210
			+22.5%		-29.1%
	Sadness	0.422	p=0.049	0.517	p=0.014	0.366
			+39.6%		-12%
	Causation (because, effect, hence)	0.914	p=0.010	1.276	p=0.065*	1.124
			+12.7%		-25.4%
	Tentative (maybe, perhaps, guess)	0.825	p=0.053*	0.930	p=0.002	0.694
			+6.7%		+46.8%
	Inhibition (block, constrain)	0.276	p=0.196	0.293	p=0.001	0.430
			-33%		+60.7%
	Assent (agree, OK, yes)	1.442	p=0.001	0.972	p=0.000	1.562

* These links are directionally significant

Acknowledgements

The authors contributed equally to this research. We would like to thank Ashlee Humphreys and the anonymous reviewers for their helpful suggestions, guidance and encouragements. For their comments on previous versions of this paper, we would like to thank Karim Ben Slimane, Bernard Forgues and Bernard Leca. We are also grateful to the participants at the AIMS, AFM and EGOS conferences in 2018 and the 'Bringing institutional theory to marketing' workshop in 2017 for their feedbacks. All errors are our own. *Corresponding author : Helene Delacour -University of Lorraine -IAE School of Management -13 rue Michel Ney -54 000 Nancy -France -helene.delacour@univ-lorraine.fr -+ 33 6 62 12 02 88


Dr Clémence Duvillier
email: cduvillier@chi-poissy-st-germain.fr

Thibaud Quibel

Céline Felsenheld

Lauriane Hupin- Genty

Camille Cohen

François Vialard

CELL-FREE DNA FRACTION: CAN IT BE USED TO EVALUATE THE RISK OF OBSTETRICAL ISSUES? Short title: Cell-free DNA fraction and obstetrical issues

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

INTRODUCTION

Depuis que la technique de recherche de l'ADN foetal libre circulant (ADNlc) dans le sang maternel a été décrite en 1997 [START_REF] Lo | Presence of fetal DNA in maternal plasma and serum[END_REF], de nombreuses études ont été effectuées pour évaluer la signification clinique et ses potentielles applications. Du fait de sa fiabilité, ce test est majoritairement utilisé pour le dépistage des aneuploïdies dites communes (trisomie 21, 18 et 13) [START_REF] Fairbrother | Clinical experience of noninvasive prenatal testing with cell-free DNA for fetal trisomies 21, 18, and 13, in a general screening population: Clinical experience of NIPT[END_REF][START_REF] De | Mise en oeuvre du screening génétique prénatal non invasif de la trisomie 21 (Syndrome de Down) dans la pratique des soins de santé en Belgique[END_REF]. En France, la Haute Autorité de Santé recommande son utilisation comme un test de dépistage de deuxième intention pour une population à risque de trisomie 21 (4) et le rembourse depuis le 20 janvier 2019 (publication de l'arrêté du 14 décembre 2018).

Au delà de cette application, une association entre la fraction d'ADNlc dans le sang maternel en début de grossesse et les complications obstétricales a été recherchée [START_REF] Farina | High levels of fetal cell-free DNA in maternal serum: A risk factor for spontaneous preterm delivery[END_REF][START_REF] Dugoff | Cellfree DNA fetal fraction and preterm birth[END_REF][START_REF] Lazar | Relationship of circulating cell-free DNA levels to cell-free fetal DNA levels, clinical characteristics and laboratory parameters in preeclampsia[END_REF]. Ces études sont basées sur une hypothèse biologique. L'ADNlc provient en effet de l'apoptose et de la nécrose du syncytio-trophoblaste [START_REF] Register | Variability of Serum Soluble Intercellular Adhesion Molecule-1 Measurements Attributable to a Common Polymorphism[END_REF]. Ainsi le taux d'ADNlc serait lié à la taille du placenta, à son fonctionnement propre et taux d'apoptose trophoblastique de celui-ci. Les mesures d'ADNlc et de fraction foetale pourraient donc être utilisées comme un marqueur de dépistage des troubles placentaires tels que la pré-éclampsie, le retard de croissance in-utéro ou l'accouchement prématuré [START_REF] Taglauer | Review: Cell-free fetal DNA in the maternal circulation as an indication of placental health and disease[END_REF].

De nombreux travaux ont été réalisés sur la pré-éclampsie, dont la prévalence représente 2% des grossesses. Celle-ci peut devenir symptomatique à partir de 20SA mais se développe de manière infra-clinique dès le premier trimestre, correspondant à un défaut d'invasion des cellules trophoblastiques dans les artères spiralées de l'utérus [START_REF] Duley | The Global Impact of Pre-eclampsia and Eclampsia[END_REF][START_REF] Lecarpentier | Physiopathologie de la pré-éclampsie[END_REF]. Les meilleurs facteurs prédictifs connus à ce jour sont les éléments cliniques (facteurs de risque), échographique (doppler des artères utérines) et biologiques (augmentation de l'HCG, PAPP-A<0,4 MoM, dosage du PLGF) [START_REF] Zeisler | Predictive Value of the sFlt-1:PlGF Ratio in Women with Suspected Preeclampsia[END_REF][START_REF] Ranta | Decreased PAPP-A is associated with preeclampsia, premature delivery and small for gestational age infants but not with placental abruption[END_REF]. La recherche de facteurs prédictifs est d'autant plus importante qu'un traitement préventif par aspirine, débuté précocement dans la grossesse améliore le pronostic materno-foetal [START_REF] Askie | Antiplatelet agents for prevention of pre-eclampsia: a meta-analysis of individual patient data[END_REF].

Les travaux étudiant cette association ont été réalisés soit au premier trimestre soit au moment de la survenue de la complication. L'objectif de notre travail était de rechercher une association entre la fraction foetale et les issues de grossesse, le test de l'ADNlc étant intégré dans la stratégie de dépistage recommandée en France. Nous avons dans un premier temps réalisé une analyse descriptive de la population.

METHODES

Nous avons ensuite choisi de faire une analyse en sous-groupes en divisant notre population selon la fraction foetale obtenue. Nous avons ainsi étudié un groupe "fraction foetale basse" correspondant aux patientes ayant comme résultat une fraction foetale inférieure au 10 ème percentile, un groupe "fraction foetale élevée" avec une fraction foetale supérieure au 90 ème percentile et un groupe "fraction foetale normale" que nous avons appelé groupe contrôle. Nous avons ensuite réalisé une étude en sous-groupes en comparant d'une part le groupe "fraction foetale basse" au groupe témoin (FF normale) et d'autre part le groupe "fraction foetale élevée" au groupe témoin. La fraction foetale avait une distribution normale au sein de notre population. Nous avons sélectionné le groupe "fraction foetale basse" en conservant les patientes dont la FF était inférieure à 8,5% soit le 10 ème percentile et le groupe "fraction foetale élevée" avec les patientes dont la FF était supérieure à 21,5% soit le 90 ème percentile.

En comparant le groupe "fraction foetale basse" au groupe contrôle, nous avons retrouvé une différence significative sur l'IMC des patientes avec une augmentation de la proportion de patientes obèses dans le groupe "fraction foetale basse" avec respectivement 38,1% versus 5,8%, p<0,01 (Tableau 2). Nous n'avons pas retrouvé de différence significative entre les deux groupes concernant l'âge maternel, l'âge gestationnel et le recours à la procréation médicalement assistée.

Concernant le critère de jugement principal (critère composite regroupant la survenue d'accouchement prématuré, d'une pré-éclampsie, d'un retard de croissance intra-utérin ou d'une hypotrophie à la naissance), 17% de grossesses avaient une complication. Il n'y avait pas de différence significative sur la survenue de complication entre les groupes (p>0,99). La proportion de pré-éclampsie et de retard de croissance in utero n'était statistiquement pas différente entre les deux groupes. Nous avons retrouvé une tendance à une augmentation des accouchements prématurés dans le groupe "fraction foetale basse", 9,6% versus 2,7% (p=0,07) (Tableau 2).

Lorsque nous avons comparé le groupe "fraction foetale élevée" au groupe contrôle, nous n'avons trouvé comme différence significative que le terme au moment du prélèvement (21,5SA et 16,7SA respectivement), p<0,01 (Tableau 3).

Nous avons enfin réalisé une courbe ROC et calculé l'aire sous la courbe pour évaluer la pertinence de la fraction foetale dans la prédiction de la survenue d'une complication obstétricale (Figure 2). La courbe obtenue était quasiment une droite et l'AUC était 0,504.

Nous avons reproduit la même démarche pour la pré-éclampsie (Figure 3) et pour la survenue d'un accouchement prématuré (Figure 3). Les AUC étaient respectivement pour la pré-éclampsie de 0,64 et 0,66. Cependant, par analyse graphique, nous avons conclu que seule la courbe ROC "fraction foetale et accouchement prématuré" paraissait interprétable sans pour autant pouvoir fixer un seuil de fraction foetale de manière satisfaisante.

DISCUSSION

Nous avons montré que la proportion de survenue de complications obstétricales n'était pas significativement liée à la quantité de fraction foetale circulant dans le sang maternel. Nous avons toutefois retrouvé une tendance à une augmentation du taux d'accouchement prématuré dans le groupe de patientes ayant une fraction foetale inférieure à 8,5%. Le taux variait de 2,7% à 9,6% sans que cela soit significatif (p=0,07).

Plusieurs facteurs influençant le taux d'ADNlc ont été identifiés. La fraction foetale augmente avec l'âge gestationnel et diminue avec l'indice de masse corporelle et l'existence d'une trisomie 13 ou 18 [START_REF] Zhou | Effects of Maternal and Fetal Characteristics on Cell-Free Fetal DNA Fraction in Maternal Plasma[END_REF]. De plus, une PAPP-A basse ou un HCG élevé sont associés à une fraction foetale basse [START_REF] Ashoor | Fetal fraction in maternal plasma cell-free DNA at 11-13 weeks' gestation: relation to maternal and fetal characteristics: Fetal fraction in maternal plasma cellfree DNA[END_REF][START_REF] Ashoor | Fetal Fraction in Maternal Plasma Cell-Free DNA at 11-13 Weeks' Gestation: Effect of Maternal and Fetal Factors[END_REF][START_REF] Canick | The impact of maternal plasma DNA fetal fraction on next generation sequencing tests for common fetal aneuploidies: Fetal fraction and noninvasive testing[END_REF][START_REF] Revello | Screening for trisomies by cell-free DNA testing of maternal blood: consequences of a failed result: Failed cell-free DNA test[END_REF][START_REF] Scott | Factors affecting cell-free DNA fetal fraction and the consequences for test accuracy[END_REF]. Ces éléments ont été retrouvés dans notre étude puisque l'âge gestationnel était significativement plus élevé dans le groupe "fraction foetale élevée" et la proportion de patientes obèses significativement plus élevée dans le groupe "fraction foetale basse".

Un autre point fort de cette étude est que nous avons obtenu les données des issues obstétricales. Nous avons donc pu comparer la survenue des complications obstétricales réelles dans chacun des groupes, ce qui nous paraissait plus informatif que la comparaison de la fraction foetale à d'autres tests de dépistage sans avoir l'issue de grossesse.

Les études publiées sur l'association entre la fraction foetale et les pathologies maternelles, vasculaires (pré-éclampsie, retard de croissance in utero, petit poids de naissance) ou non (accouchement prématuré) sont discordantes. Concernant la pré-éclampsie, il existe des arguments physiopathologiques pour penser à une association entre pré-éclampsie et élévation de la fraction foetale. En effet, une mauvaise placentation conduisant à une ischémie placentaire peut être la cause d'une augmentation de l'apoptose et nécrose du syncytio-trophoblaste, à l'origine de l'ADNlc. On peut également penser que la diminution de la clairance rénale chez les patientes pré-éclamptiques peut augmenter le taux d'ADNlc dans la circulation maternelle. Enfin, les problèmes de placentation étant précoces dans la grossesse et antérieurs aux symptômes cliniques de pré-éclampsie, on pourrait penser que la fraction foetale d'ADNlc serait augmentée également précocement. Cependant, certaines études retrouvaient une fraction foetale élevée en cas de risque de survenue de la pathologie [START_REF] Farina | Total cellfree DNA(β-globin gene) distribution in maternal plasma at the second trimester: a new prospective for preeclampsia screening[END_REF][START_REF] Galbiati | Evaluation of a panel of circulating DNA, RNA and protein potential markers for pathologies of pregnancy[END_REF][START_REF] Cotter | Increased fetal DNA in the maternal circulation in early pregnancy is associated with an increased risk of preeclampsia[END_REF] tandis que d'autres n'objectivaient pas de différence significative [START_REF] Crowley | Free fetal DNA is not increased before 20 weeks in intrauterine growth restriction or pre-eclampsia[END_REF][START_REF] Poon | Maternal Plasma Cell-Free Fetal and Maternal DNA at 11-13 Weeks' Gestation: Relation to Fetal and Maternal Characteristics and Pregnancy Outcomes[END_REF]. Ces études étaient souvent basées sur un nombre de cas de prééclampsie assez faible. L'étude de Rolnick a montré une association entre fraction foetale basse et une augmentation du risque de développer une pré-éclampsie [START_REF] Rolnik | Association between fetal fraction on cell-free DNA testing and first-trimester markers for pre-eclampsia: First-trimester markers for pre-eclampsia and cfDNA fetal fraction[END_REF].

Cependant l'étude comparait la fraction foetale à des facteurs prédictifs reconnus de pré-éclampsie comme le doppler des artères utérines et la pression artérielle moyenne maternelle mais sans information sur la survenue effective de la pathologie. La métaanalyse de Contro concluait à une valeur prédictive trop basse et non significative de la fraction foetale d'ADNlc pour être utilisée en pratique clinique. Cependant une fraction foetale élevée était décrit comme un marqueur de survenue d'une prééclampsie [START_REF] Contro | Cell-Free Fetal DNA for the Prediction of Pre-Eclampsia at the First and Second Trimesters: A Systematic Review and Meta-Analysis[END_REF]. L'âge gestationnel moyen de notre population d'étude était de 17SA.

Elle correspondait à une stratégie de dépistage de la trisomie 21 avec le test de l'ADNlc réalisé en deuxième intention mais le terme était cependant tardif. L'apoptose trophoblastique n'évolue probablement pas entre 12 et 17SA, nos résultats n'étaient donc pas en faveur d'une association entre fraction foetale élevée et pré-éclampsie. En revanche cette différence de population et de terme peut expliquer l'absence de lien retrouvé concernant l'hypothèse de fraction foetale basse et pré-éclampsie. Par ailleurs, la pertinence clinique de l'ADNlc à ce terme était limitée car pour prévenir le développement d'une pré-éclampsie l'aspirine doit être débutée dès le premier trimestre [START_REF] Rolnik | Aspirin versus Placebo in Pregnancies at High Risk for Preterm Preeclampsia[END_REF].

Les mêmes discordances existent pour l'accouchement prématuré [START_REF] Rolnik | Association between fetal fraction on cell-free DNA testing and first-trimester markers for pre-eclampsia: First-trimester markers for pre-eclampsia and cfDNA fetal fraction[END_REF][START_REF] Alberry | Quantification of cell free fetal DNA in maternal plasma in normal pregnancies and in pregnancies with placental dysfunction[END_REF][START_REF] Nakib | Total and Fetal Cell-Free DNA Analysis in Maternal Blood as Markers of Placental Insufficiency in Intrauterine Growth Restriction[END_REF][START_REF] Sekizawa | Cell-free fetal DNA in the plasma of pregnant women with severe fetal growth restriction[END_REF]. Deux études ont montré que les patientes ayant une fraction foetale élevée étaient plus à risque d'accouchement prématuré [START_REF] Farina | High levels of fetal cell-free DNA in maternal serum: A risk factor for spontaneous preterm delivery[END_REF][START_REF] Leung | Maternal plasma fetal DNA as a marker for preterm labour[END_REF]. Dans ces études, les prélèvements étaient réalisés au moment de la complication. Plusieurs études ont au contraire montré l'absence d'association entre fraction foetale et terme d'accouchement. Cependant dans ces études, la fraction foetale était prélevée au premier trimestre [START_REF] Poon | Maternal Plasma Cell-Free Fetal and Maternal DNA at 11-13 Weeks' Gestation: Relation to Fetal and Maternal Characteristics and Pregnancy Outcomes[END_REF][START_REF] Dugoff | Cellfree DNA fetal fraction and preterm birth[END_REF][START_REF] Quezada | Fetal fraction of cell-free DNA in maternal plasma in the prediction of spontaneous preterm delivery[END_REF]. Lorsque la fraction foetale est prélevée au deuxième trimestre, entre 14SA et 20SA pour l'étude de Dugoff et entre 23 et 28SA pour celle publiée par Jakobsen, une association entre accouchement prématuré et fraction foetale élevée a été retrouvée [START_REF] Dugoff | Cellfree DNA fetal fraction and preterm birth[END_REF][START_REF] Jakobsen | High levels of fetal DNA are associated with increased risk of spontaneous preterm delivery: Cell free fetal DNA and spontaneous preterm delivery[END_REF]. Plusieurs autres études ne retrouvent cependant pas cette association bien que l'étude de la fraction foetale ait été réalisée au même âge gestationnel [START_REF] Stein | Cell-free fetal DNA and adverse outcome in low risk pregnancies[END_REF][START_REF] Illanes | Free fetal DNA levels in patients at risk of preterm labour: Free fetal DNA levels in patients at risk of preterm labour[END_REF][START_REF] Bauer | A prospective analysis of cell-free fetal DNA concentration in maternal plasma as an indicator for adverse pregnancy outcome[END_REF]. Dans notre étude, l'âge gestationnel moyen au prélèvement était de 17SA. Le terme au moment de l'évaluation de la fraction foetale semble donc être un élément primordial pour l'évaluation de l'association entre fraction foetale et risque d'accouchement prématuré. Une des limites principales de notre étude était la proportion importante de patientes perdues de vue. Ce nombre important était probablement dû au mode de recueil des issues obstétricales par appel téléphonique. Lorsque nous avons étudié les caractéristiques de la population des patientes perdues de vue, les résultats étaient comparables à ceux de notre population d'étude. En particulier, l'âge gestationnel moyen au moment du prélèvement était de 17SA et la fraction foetale moyenne de 13,9%. Nous avons donc considéré que ce nombre important de patientes perdues de vue n'induisait pas de biais de sélection dans notre étude.

Le mode de recueil de notre critère de jugement principal était par appel téléphonique et basé sur le discours des patientes. La fiabilité des données médicales était donc de ce fait limitée.

Enfin, la prévalence des complications obstétricales était faible dans notre population d'étude. Nous avons retrouvé 1,9% de pré-éclampsie, 11,8% de retard de croissance in utero et enfants hypotrophes à la naissance et 3,4% d'accouchements prématurés. Ces données étaient inférieures à la prévalence publiée en France selon l'Inserm, soit 5% pour la pré-éclampsie et 7,4% pour la prématurité [START_REF] Torchin | Épidémiologie de la prématurité: prévalence, évolution, devenir des enfants[END_REF]. Cette faible prévalence pourrait être liée au nombre important des patientes n'ayant pas répondu. En effet la population des perdues de vue comprend souvent plus d'issues défavorables.

De nouvelles études basées sur l'ARN et sur l'ADN associé à l'exosome ont été initiées. Ces techniques pourraient être une nouvelle piste pour expliquer la survenue de complications obstétricales et permettre leur prévention [START_REF] Konečná | Exosomes-Associated DNA-New Marker in Pregnancy Complications[END_REF][START_REF] Ngo | Noninvasive blood tests for fetal development predict gestational age and preterm delivery[END_REF].

  Nous avons réalisé une étude rétrospective non interventionnelle au sein du centre hospitalier intercommunal de Poissy Saint-Germain (CHIPS). Nous avons inclus toutes les patientes ayant eu une consultation de cytogénétique en vue de la réalisation d'un test de l'ADNlc dans notre centre entre le 1 er janvier 2015 et le 31 décembre 2016. Nous n'avons par la suite inclus que les grossesses singletons, puisque la fraction foetale est directement liée au nombre de foetus, et dont les issues de grossesse étaient connues. Le test de l'ADNlc a été réalisé grâce au test de dépistage Harmony TM commercialisé par le laboratoire Roche, test basé sur une technique ciblée donnant une estimation de la surreprésentation du chromosome d'intérêt. Les issues de grossesse ont été secondairement recueillies par téléphone auprès des patientes lorsqu'elles nous avaient donné leur consentement. Un accord auprès de la CNIL (Commission Nationale de l'Informatique et des Libertés) avec la maternité de Poissy autorise l'utilisation de données observationnelles des dossiers médicaux anonymisés. Le critère de jugement principal était la survenue d'une complication obstétricale. Il s'agissait d'un critère composite regroupant la survenue d'accouchement prématuré, d'une pré-éclampsie, d'un retard de croissance intra-utérin ou d'une hypotrophie à la naissance (Estimation du poids foetal <10ème percentile ou poids de naissance <10ème percentile selon la courbe Audipog).

  Nous avons enfin étudié les performances de la fraction foetale pour évaluer le risque de survenue de complications obstétricales et en particulier pour la pré-éclampsie et le risque d'accouchement prématuré. Les résultats descriptifs ont été rapportés en pourcentages pour les variables catégorielles et en moyenne et écart-type pour les variables quantitatives. Les pourcentages ont été comparés par test de Chi2 et les moyennes par un test de Student. Les performances de la fraction foetale ont été évaluées à l'aide de courbe ROC et de l'aire sous la courbe (AUC). Toutes les analyses ont été réalisées au seuil de 5% à l'aide du logiciel R studio version 1.0.136. RESULTATS 576 patientes ont été reçues en consultation de cytogénétique au CHIPS de janvier 2015 à décembre 2017. Après exclusion des grossesses gémellaires et des patientes dont les issues de grossesse étaient manquantes, notre population d'étude regroupait au final 417 patientes (Figure 1). Le test de l'ADNlc a été réalisé dans 72,7% des cas en deuxième intention pour des patientes appartenant à un groupe à risque entre 1/51 et 1/1000 suite au dépistage par les marqueurs sériques du premier ou du deuxième trimestre. L'ADNlc avait été prélevé dans 11% des cas pour anxiété maternelle. Le reste des prélèvements a été réalisé pour antécédent d'aneuploïdie, signes échographiques mineurs (fémur court, pyélectasie mineure, intestins hyperéchogènes, persistance de kystes des plexus choroïdes, spot mitral) ou âge maternel de plus de 38 ans sans dépistage combiné réalisé (Tableau 1). Le test était négatif pour 411 patientes et positif pour la trisomie 21 chez une patiente. Sur l'ensemble de la cohorte, 5 tests d'ADNlc étaient sans résultat: 3 échecs ont été observés malgré la réalisation d'un deuxième prélèvement, ce qui représentait 0,72% de la population (Tableau 1) et 2 prélèvements étaient "nonrendus". L'absence de résultat était expliquée par le fait qu'aucun résultat n'était donné par le laboratoire Roche pour les fractions les plus basses. Concernant l'âge gestationnel moyen au moment du prélèvement, il était de 17,1 semaines d'aménorrhée dans notre population. La fraction foetale moyenne obtenue était de 14,3%, variant de 4,1% à 37,8%. Concernant les issues de grossesse, 8 prééclampsies (1,9%), 48 retards de croissance in utero ou hypotrophie néonatale (11,8%) et 14 accouchements prématurés (3,4%) (Tableau 1).

  La tendance à cette association pourrait être dû à l'IMC significativement plus important chez les patientes de ce groupe. En effet les patientes obèses ont plus de complications obstétricales. Du fait de la faible prévalence de notre critère de jugement principal nous n'avions pas pu réalisé d'ajustement sur ce facteur de confusion.La réalisation de courbes ROC nous a également permis de montrer que le choix du seuil de fraction foetale dans nos différents groupes était arbitraire et ce, en particulier pour la survenue des complications obstétricales globales. Ces courbes peuvent permettre d'expliquer pourquoi les résultats de la littérature existante sont discordants.Dans notre étude, il paraît également difficile d'interpréter les résultats concernant la pré-éclampsie.Seule l'association entre fraction foetale et accouchement prématuré paraît interprétable quoique peu significative.Notre population était composée à 73% de patientes appartenant à un groupe à risque fort ou intermédiaire pour la trisomie 21. Nous avons déjà discuté qu'en cas de trisomies 13 ou 18 (20) la fraction foetale était abaissée. Cependant dans notre population, seul un cas de trisomie 21 a été effectivement diagnostiqué et cette aneuploïdie n'influe pas sur la fraction foetale[START_REF] Zhou | Effects of Maternal and Fetal Characteristics on Cell-Free Fetal DNA Fraction in Maternal Plasma[END_REF]. Nous pouvions donc considérer que ce choix de population n'avait pas de retentissement sur la fraction foetale. De plus, le test de l'ADNlc est utilisé en France, selon les recommandations de la Haute Autorité de Santé comme un test de dépistage de deuxième intention (4). Il est donc majoritairement réalisé chez des patientes similaires à celles de notre étude, ce qui augmente la validité externe de nos résultats.

CONCLUSION

  Nous n'avons pas retrouvé d'association entre la fraction foetale d'ADNlc dans le sang maternel et la survenue de complications obstétricales. Nous avons retrouvé une tendance entre fraction foetale basse et accouchement prématuré, cependant la prévalence de cette complication était très faible dans notre population. Il serait donc intéressant de poursuivre l'étude de cette association, d'autant plus qu'avec l'augmentation de la prescription du test de l'ADNlc en France, la fraction foetale est un outil de plus en plus disponible. 576 patientes reçues en cytogénétique 536 singletons 40 grossesses gémellaires 119 perdues de vue 417 DPNI réalisés avec issue de grossesse connue

Figure 1 :

 1 Figure 1: Diagramme de flux

Fig 3 :

 3 Fig 3 : courbes ROC : fraction foetale et pré-éclampsie, fraction foetale et accouchement prématuré


Hajer Rmadi

Pauline Maillot

R Artico

S Hanneton

G Dietrich

E Duron

Cybersickness and acceptance of immersive head-mounted virtual reality in older adults in nursing homes

come

Given the frequency of health problems and anxiety among older adults with diasbilities living in nursing homes, this study aims to evaluate the occurrence of cybersickness among elderly and their acceptance of VR technology (i.e., anxiety to VR).

Aim

(1) Institut des Sciences du Sport-Santé de Paris (URP3625 -I3SP), Université Paris Cité, Paris ; (2) Laboratoire Complexité, Innovations, Activités Motrices et Sportives (CIAMS, EA4532), Université Paris-Saclay, Orsay ; (3) Assistance Publique -Hôpitaux universitaires Paris-Saclay, AP-HP, Hôpital Paul Brousse, Service de gériatrie, Villejuif, France. (4) Université Paris-Saclay, Inserm, CESP, Team MOODS, 94270 Le Kremlin-Bicêtre, France.

H. Rmadi (1) ; P. Maillot (1) ; R. Artico (2) ; S. Hanneton (1) ; G. Dietrich (1) ; E. Duron (3) (4)

Cybersickness and acceptance of immersive head-mounted virtual reality in older adults in nursing homes

• 36 participants (age = 89 ± 5.3; MMSE = 16 ± 3) from 8 nursing homes.

• Three VR sessions (S1, S2, S3) each consisting of a different 7-minutes immersion.

• An assessment of the Trait Anxiety (TA) using the State Trait Anxiety Inventory (STAI) form Y-B (Spielberger, 1983) was performed before S1 and at the end of S3. • State Anxiety (SA) and Heart Rate (HR) were evaluated before and after each session. • Subjects completed the Simulator Sickness Questionnaire (SSQ) (Kennedy et al., 1993) and gave feedback about realism, immersion, perceived pleasure, intention to use, and perceived usefulness for each session using an acceptance questionnaire (total score from 8 to 48).

Walk in the forest at the rhythm of seasons

Grand Canyon

Animals in the nature

Interpretation and perspectives

Fig. 1 .Fig. 2 .

 12 Fig. 1. A Photo of a participant during a session

Results

• Two participants left the study for intolerance to VR and one for lack of motivation. • Cybersickness was noted on 21 % of sessions. The SSQ score did not vary over the sessions F (2, 32 ) = 1,22; p = .33. • HR measurements did not vary between before and after sessions F (2, 31) = 2,51; p = .08. • SA decreased significantly after each session F(32, 160) = 6,12 ; p< 0,001. • The acceptance score was 40.1± 7.1 out of 48 and did not vary between sessions F (2, 32) = 0,24 : p = .78 • Comparison of age, MMSE and TA scores between participants who suffered cybersickness (SSQ score >10) and those who had an SSQ score <10 does not show any differences. • VR seems to be well accepted among elderly dependent subjects with disabilities. • Age, MMSE and anxiety do not appear to be predictors of cybersickness. • Virtual Reality (VR) is used as an exposure technique for cognitive and affective disorders in the aging population (Skurla et al., 2022).

• VR experiences often elicit cybersickness.

• Cybersickness is associated with physiological effects, anxiety, and dropouts (Stanney et al., 2020;Ling et al., 2011).