GPs' practices when prescribing buprenorphine in primary care: A survey among the Sentinelles network

INTRODUCTION

France is a leading country for opioid agonist treatment providing, with a predominance of buprenorphine. General practitioners (GPs) are the main prescribers of buprenorphine, but they seem to be less involved over the last 10 years. This work is the second part of a larger study analysing buprenorphine prescribing among French GPs working in primary care, and aims to describe GPs' practices when prescribing buprenorphine.

METHODS

This is a cross-sectional study conducted in France from March to July 2021 among a sample of GPs in the Sentinelles network, a national epidemiologic surveillance system. Data about the last situations of initiation and renewal of buprenorphine were collected.

RESULTS

Among the 237 participants (34.3% response rate), 156 responded to the questionnaire about the last situation of renewal and 41 about the last situation of initiation. The last initiation occurred more than 12 months earlier for 46.3% of respondents, whereas the last renewal occurred less than 1 month ago for 68.6%. There was an over-representation of the male gender among the patients who were consulting (initiation 70.7%, renewal 68.6%). A majority of patients had an illicit opioid use disorder (initiation 78.0%, renewal 82.7%). Overall, GPs were involved in the general care of patients with opioids use disorder and in opioids harm reduction (initiation 87.8% and 82.9%, renewal 88.5% and 51.9%).

CONCLUSION

Among buprenorphine prescribers, initiations were infrequent unlike renewals and involved mainly illicit opioid users.

[Prevention of pertussis in newborns: Should pregnant women be vaccinated at each pregnancy?]

Pertussis is a respiratory disease that can be fatal at all ages but especially in infants before their mandatory vaccination. Recent epidemiological data shows a decrease in the number of pertussis cases, but a resurgence cannot be excluded in the coming years due to the cyclic evolution of the disease and the loosening of hygiene measures. Two approaches are used to protect infants before their vaccination: vaccination of the mother during pregnancy and vaccination of all the infant's close relatives (cocooning). The vaccination of the mother during pregnancy is more effective. The uncertain risk of chorioamniotitis associated with vaccination during pregnancy is insufficient to question this strategy.

Influenza-like illness in individuals treated with immunosuppressants, biologics, and/or systemic corticosteroids for autoimmune or chronic inflammatory disease: A crowdsourced cohort study, France, 2017-2018

BACKGROUND

Influenza-like illness (ILI) incidence estimates in individuals treated with immunosuppressants and/or biologics and/or corticosteroid for an autoimmune or chronic inflammatory disease are scarce. We compared the ILI incidence among immunocompromised population and the general population.

METHOD

We conducted a prospective cohort study during the 2017-2018 seasonal influenza epidemic, on the GrippeNet.fr electronic platform, which allows the collection of epidemiological crowdsourced data on ILI, directly from the French general population. The immunocompromised population were adults treated with systemic corticosteroids, immunosuppressants, and/or biologics for an autoimmune or chronic inflammatory disease, recruited directly on GrippeNet.fr and also among patients of the departments of a single university hospital that were asked to incorporate GrippeNet.fr. The general population consisted of adults reporting none of the above treatments or diseases participating in GrippeNet.fr. The incidence of ILI was estimated on a weekly basis and compared between the immunocompromised population and the general population, during the seasonal influenza epidemic.

RESULTS

Among the 318 immunocompromised patients assessed for eligibility, 177 were included. During the 2017-2018 seasonal influenza epidemic period, immunocompromised population had 1.59 (95% CI: 1.13-2.20) higher odds to experience an ILI episode, compared to the general population (N = 5358). An influenza vaccination was reported by 58% of the immunocompromised population, compared to 41% of the general population (p < 0.001).

CONCLUSION

During a seasonal influenza epidemic period, the incidence of influenza-like illness was higher in patients treated with immunosuppressants, biologics, and/or corticosteroids for an autoimmune or chronic inflammatory disease, compared to the general population.

Attitudes towards booster, testing and isolation, and their impact on COVID-19 response in winter 2022/2023 in France, Belgium, and Italy: a cross-sectional survey and modelling study

Background

European countries are focusing on testing, isolation, and boosting strategies to counter the 2022/2023 winter surge due to SARS-CoV-2 Omicron subvariants. However, widespread pandemic fatigue and limited compliance potentially undermine mitigation efforts.

Methods

To establish a baseline for interventions, we ran a multicountry survey to assess respondents’ willingness to receive booster vaccination and comply with testing and isolation mandates. Integrating survey and estimated immunity data in a branching process epidemic spreading model, we evaluated the effectiveness and costs of current protocols in France, Belgium, and Italy to manage the winter wave.

Findings

The vast majority of survey participants (N = 4594) was willing to adhere to testing (>91%) and rapid isolation (>88%) across the three countries. Pronounced differences emerged in the declared senior adherence to booster vaccination (73% in France, 94% in Belgium, 86% in Italy). Epidemic model results estimate that testing and isolation protocols would confer significant benefit in reducing transmission (17–24% reduction, from R = 1.6 to R = 1.3 in France and Belgium, to R = 1.2 in Italy) with declared adherence. Achieving a mitigating level similar to the French protocol, the Belgian protocol would require 35% fewer tests (from 1 test to 0.65 test per infected person) and avoid the long isolation periods of the Italian protocol (average of 6 days vs. 11). A cost barrier to test would significantly decrease adherence in France and Belgium, undermining protocols’ effectiveness.

Interpretation

Simpler mandates for isolation may increase awareness and actual compliance, reducing testing costs, without compromising mitigation. High booster vaccination uptake remains key for the control of the winter wave.

Funding

The 10.13039/501100000780European Commission, ANRS–Maladies Infectieuses Émergentes, the Agence Nationale de la Recherche, the Chaires Blaise Pascal Program of the Île-de-France region.

Prescribing buprenorphine for opioid use disorder in primary care: A survey of French general practitioners in the Sentinelles network

INTRODUCTION

Although opioid substitution coverage in France is high and patient care with buprenorphine is mainly managed by general practitioners (GPs), buprenorphine sales have been decreasing since 2011, suggesting that French GPs are prescribing less buprenorphine. Yet this possible change in GP practices has not yet been investigated. This study aimed to examine primary care GPs' opinions about buprenorphine and habits related to prescribing buprenorphine.

METHODS

The study team conducted a cross-sectional survey from March 2021 to July 2021 among a sample of GPs in the Sentinelles network, a French epidemiologic surveillance system based on primary care practitioners. The study collected information about substance use disorder (SUD) training, opinions on buprenorphine, and habits related to buprenorphine prescription were collected (initiation and renewal within the past two years).

FINDINGS

Among the 237 participants (34 % response rate), 15.2 % reported having had specific training for SUD management. A majority reported a very positive (16 %) or positive (63.7 %) opinion of buprenorphine. Most participants agreed (61.2 %) or strongly agreed (31.2 %) that buprenorphine was efficacious in the treatment of illicit opioid use disorder. Of the 206 GPs who reported having treated patients with opioid use disorder in the past two years, 47 (22.8 %) had initiated a buprenorphine prescription, whereas 177 (85.9 %) had renewed a buprenorphine prescription. Previous SUD training was associated with initiating buprenorphine (OR 4.66; 95 % CI [2.15-10.08]), while female gender was associated with not initiating buprenorphine prescribing (OR 0.46; 95 % CI [0.22-0.98]).

CONCLUSION

A sample of French GPs who work in primary care has a positive view of buprenorphine, but the absence of SUD training among this population may be a barrier to their prescribing buprenorphine.

Epidemiology of acute gastroenteritis in France from November 2019-August 2021, in light of reported adherence to COVID-19 barrier measures

Since the start of the COVID-19 pandemic, French health authorities have encouraged barrier measures and implemented three lockdowns to slow SARS-CoV-2 transmission. We aimed to examine the impact of these measures on the epidemiology of acute gastroenteritis (AGE) in France, from November 2019 to August 2021. We describe trends in AGE indicators from syndromic surveillance and a sentinel surveillance network. Additionally, we describe reported AGE illness data from a community based cohort, and frequencies of adherence to COVID-19 barrier measures from repeated quantitative surveys. From week 7 in 2020, all AGE indicators reached the lowest levels observed since the last decade. During the first lockdown, the median incidence rate reported by the sentinel network was 32 per 100,000 inhabitants, 1.9 times lower than the minimum registered during the 2010-2019 period. Low activity persisted until April 2021. Reported illness from the community cohort mirrored these trends. Adherence to COVID-19 barrier measures was highest during the first lockdown, coinciding with the steep decrease in AGE incidence. Among children under 5 years, AGE incidence increased after the third lockdown in June and July 2021, but remained lower than previous winter-season peaks. Our study indicates that a reduction in adherence to COVID-19 barrier measures, and the end of the lockdowns, coincided with an increase in AGE incidence, particularly among young children. We therefore strongly recommend maintaining adherence to barrier measures in order to in order to limit the transmission of AGE related pathogens.

Vegetarian and Vegan Diets: Beliefs and Attitudes of General Practitioners and Pediatricians in France

Studies suggest a decreasing trend in the consumption of meat products and a growing interest in vegetarian diets. Medical support may be relevant, especially when switching to a vegan diet. Our objective was to describe the beliefs and attitudes of primary care physicians toward vegetarian diets. A cross-sectional survey was conducted among general practitioners and pediatricians thorough a questionnaire including socio-demographic characteristics, specific care to vegetarians, and the risks and benefits of vegetarian diets according to physicians. Out of the 177 participating physicians, 104 (59%) have seen at least one vegetarian patient in consultation in the last three months. Half of the physicians declared that they would dissuade their patients from switching to a vegan diet (n = 88, 51%) and 14% (n = 24) from switching to an ovo-lacto-vegetarian (OLV) diet. Most physicians (n = 141, 88%) did not feel informed enough about these diets. Physicians thought that the most frequent deficiencies for OLV and vegan diets were iron (76% and 84%, respectively) and protein (45% and 79%, respectively). These results highlight the fact that French primary care physicians feel concerned by this subject and need more information on these diets. Specific recommendations would be useful to support their practice and relationship with vegetarians.

Pertussis surveillance results from a French general practitioner network, France, 2017 to 2020

Introduction

In France, three complementary surveillance networks involving hospitals and paediatrician practices currently allow pertussis surveillance among infants (<1 year old) and children (1–12 years old). Data on incidences among adolescents (13–17 years old) and adults (≥ 18 years) are scarce. In 2017, a sentinel surveillance system called Sentinelles network, was implemented among general practitioners (GPs).

Aim

The purpose of Sentinelles network is to assess pertussis incidence, monitor the cases’ age distribution and evaluate the impact of the country’s vaccination policy. We present the results from the first 4 years of this surveillance.

Methods

GPs of the French Sentinelles network reported weekly numbers of epidemiologically or laboratory-confirmed cases and their characteristics.

Results

A total of 132 cases were reported over 2017–2020. Estimated national incidence rates per 100,000 inhabitants were 17 (95% confidence interval (CI): 12–22) in 2017, 10 (95% CI: 6–14) in 2018, 15 (95% CI: 10–20) in 2019 and three (95% CI: 1–5) in 2020. The incidence rate was significantly lower in 2020 than in 2017–2019. Women were significantly more affected than men (83/132; 63% of women, p = 0.004); 66% (87/132) of cases were aged 15 years or over (median age: 31.5 years; range: 2 months–87 years). Among 37 vaccinated cases with data, 33 had received the recommended number of doses for their age.

Conclusions

These results concur with incidences reported in other European countries, and with studies showing that the incidences of several respiratory diseases decreased in 2020 during the COVID-19 pandemic. The results also suggest a shift of morbidity towards older age groups, and a rapid waning of immunity after vaccination, justifying to continue this surveillance.

Are People Optimistically Biased about the Risk of COVID-19 Infection? Lessons from the First Wave of the Pandemic in Europe

Unrealistic optimism, the underestimation of one's risk of experiencing harm, has been investigated extensively to understand better and predict behavioural responses to health threats. Prior to the COVID-19 pandemic, a relative dearth of research existed in this domain regarding epidemics, which is surprising considering that this optimistic bias has been associated with a lack of engagement in protective behaviours critical in fighting twenty-first-century, emergent, infectious diseases. The current study addresses this gap in the literature by investigating whether people demonstrated optimism bias during the first wave of the COVID-19 pandemic in Europe, how this changed over time, and whether unrealistic optimism was negatively associated with protective measures. Taking advantage of a pre-existing international participative influenza surveillance network (n = 12,378), absolute and comparative unrealistic optimism were measured at three epidemic stages (pre-, early, peak), and across four countries-France, Italy, Switzerland and the United Kingdom. Despite differences in culture and health response, similar patterns were observed across all four countries. The prevalence of unrealistic optimism appears to be influenced by the particular epidemic context. Paradoxically, whereas absolute unrealistic optimism decreased over time, comparative unrealistic optimism increased, suggesting that whilst people became increasingly accurate in assessing their personal risk, they nonetheless overestimated that for others. Comparative unrealistic optimism was negatively associated with the adoption of protective behaviours, which is worrying, given that these preventive measures are critical in tackling the spread and health burden of COVID-19. It is hoped these findings will inspire further research into sociocognitive mechanisms involved in risk appraisal.

Perceived risk of opioid use disorder secondary to opioid analgesic medication use by the general population in France

BACKGROUND

In Europe and France, the use of opioid analgesic drugs has become widespread as an option for pain management. However, their use can lead to nonmedical use and/or opioid use disorder (OUD). This work aimed to assess the perceived risk of OUD secondary to opioid analgesic drugs use by the general population.

METHODS

We conducted a cross-sectional observational study using the GrippeNet web-based cohort, comprising about 10,000 French volunteers from the general population, using a self-administered questionnaire. The main outcome was the perceived risk of OUD secondary to opioid analgesic drugs use, assessed by a 4-item scale and modeled using logistic regression (backward procedure).

RESULTS

Among 5,046 French respondents, after adjustment, 65% believed that the use of analgesic drugs could likely or very likely lead to OUD. Factors associated with perception of a higher risk were being over 50 and having heard about opioids in the media. Previous opioid use and a high level of education decreased the perception of the risk. Among those having used opioids in the past two years (N = 1770), 71.1% reported being not at all concerned by this risk. The majority of the sample perceived the risk of OUD but those having already used opioid analgesics drugs expressed no concern about this risk for themselves.

CONCLUSIONS

This finding highlight the need to reinforce warning on the package insert documents, therapeutic education and collaborative care between the prescribing general practitioners and pharmacists to increase awareness of opioid medications users on the risk of OUD.

Implementation of a top five list to identify medical overuse in general practice according to patients' viewpoint in 2019 in France

BACKGROUND

There is a current trend to reassess the adequacy of care. Establishing top five lists by involving patients is one way to address medical overuse. The objective of this study was to establish a patients' top five list in general practice in France. The secondary objective was to identify selection criteria.

METHOD

Patients from the web-based cohort GrippeNet.fr were invited to establish their top five list from 15 care procedures previously selected by general practitioners on the basis of medical overuse. The care procedures were presented on a web-interface with guides written with the help of a patient association. A questionnaire was used to explore factors that may have influenced the choices of the participants.

RESULTS

In total, 691 patients established the following top five list: 1/ Prescription of antibiotics for acute bronchitis, nasopharyngitis, otitis media with effusion, or uncomplicated influenza; 2/ Prescription of benzodiazepine and benzodiazepine-like agents for insomnia, generalised anxiety and all indications for older patients; 3/ Prescription of a homeopathic treatment (Influenzinum) for flu prevention; 4/ Prescription of antitussive or expectorant agents for acute cough or acute bronchitis care; 5/ Prescription of statins for the primary prevention of cardio-vascular risk in older patients. More than 70% of participants gave importance to the recommendations, effectiveness, and tolerance of the care procedures, whereas only half considered the cost.

CONCLUSION

This study is the first to establish a patient's top-five list in general practice. This list provides direction for deciding the main targets in limiting medical overuse.

Underdetection of cases of COVID-19 in France threatens epidemic control

As countries in Europe gradually relaxed lockdown restrictions after the first wave, test-trace-isolate strategies became critical to maintain the incidence of coronavirus disease 2019 (COVID-19) at low levels^1,2. Reviewing their shortcomings can provide elements to consider in light of the second wave that is currently underway in Europe. Here we estimate the rate of detection of symptomatic cases of COVID-19 in France after lockdown through the use of virological³ and participatory syndromic⁴ surveillance data coupled with mathematical transmission models calibrated to regional hospitalizations². Our findings indicate that around 90,000 symptomatic infections, corresponding to 9 out 10 cases, were not ascertained by the surveillance system in the first 7 weeks after lockdown from 11 May to 28 June 2020, although the test positivity rate did not exceed the 5% recommendation of the World Health Organization (WHO)⁵. The median detection rate increased from 7% (95% confidence interval, 6-8%) to 38% (35-44%) over time, with large regional variations, owing to a strengthening of the system as well as a decrease in epidemic activity. According to participatory surveillance data, only 31% of individuals with COVID-19-like symptoms consulted a doctor in the study period. This suggests that large numbers of symptomatic cases of COVID-19 did not seek medical advice despite recommendations, as confirmed by serological studies^6,7. Encouraging awareness and same-day healthcare-seeking behaviour of suspected cases of COVID-19 is critical to improve detection. However, the capacity of the system remained insufficient even at the low epidemic activity achieved after lockdown, and was predicted to deteriorate rapidly with increasing incidence of COVID-19 cases. Substantially more aggressive, targeted and efficient testing with easier access is required to act as a tool to control the COVID-19 pandemic. The testing strategy will be critical to enable partial lifting of the current restrictive measures in Europe and to avoid a third wave.

Factors associated with influenza-like-illness: a crowdsourced cohort study from 2012/13 to 2017/18

Background

Influenza generates a significant societal impact on morbidity, mortality, and associated costs. The study objective was to identify factors associated with influenza-like-illness (ILI) episodes during seasonal influenza epidemics among the general population.

Methods

A prospective study was conducted with the GrippeNet.fr crowdsourced cohort between 2012/13 and 2017/18. After having completed a yearly profile survey detailing socio-demographic, lifestyle and health characteristics, participants reported weekly data on symptoms. Factors associated with at least one ILI episode per influenza epidemic, using the European Centre for Disease Prevention and Control case definition, were analyzed through a conditional logistic regression model.

Results

From 2012/13 to 2017/18, 6992 individuals participated at least once, and 61% of them were women (n = 4258). From 11% (n = 469/4140 in 2013/14) to 29% (n = 866/2943 in 2012/13) of individuals experienced at least one ILI during an influenza epidemic. Factors associated with higher risk for ILI were: gender female (OR = 1.29, 95%CI [1.20; 1.40]), young age (< 5 years old: 3.12 [2.05; 4.68]); from 5 to 14 years old: 1.53 [1.17; 2.00]), respiratory allergies (1.27 [1.18; 1.37]), receiving a treatment for chronic disease (1.20 [1.09; 1.32]), being overweight (1.18 [1.08; 1.29]) or obese (1.28 [1.14; 1.44]), using public transport (1.17 [1.07; 1.29]) and having contact with pets (1.18 [1.09; 1.27]). Older age (≥ 75 years old: 0.70 [0.56; 0.87]) and being vaccinated against influenza (0.91 [0.84; 0.99]) were found to be protective factors for ILI.

Conclusions

This ILI risk factors analysis confirms and further completes the list of factors observed through traditional surveillance systems. It indicates that crowdsourced cohorts are effective to study ILI determinants at the population level. These findings could be used to adapt influenza prevention messages at the population level to reduce the spread of the disease.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7174-6) contains supplementary material, which is available to authorized users.

Population perception of mandatory childhood vaccination programme before its implementation, France, 2017

BackgroundVaccination policy in France was previously characterised by the coexistence of eight recommended and three mandatory vaccinations for children younger than 2 years old. These 11 vaccines are now mandatory for all children born after 1 January 2018.AimTo study the French population's opinion about this new policy and to assess factors associated with a positive opinion during this changing phase.MethodsA cross-sectional survey about vaccination was conducted from 16 November-19 December 2017 among the GrippeNet.fr cohort. Data were weighted for age, sex and education according to the French population. Univariate and multivariate analyses were performed to identify factors associated with a favourable opinion on mandatory vaccines' extension and defined in the '3Cs' model by the World Health Organization Strategic Advisory Group of Experts working group on vaccine hesitancy.ResultsOf the 3,222 participants (response rate 50.5%) and after adjustment, 64.5% agreed with the extension of mandatory vaccines. It was considered a necessary step by 68.7% of the study population, while 33.8% considered it unsafe for children and 56.9% saw it as authoritarian. Factors associated with a positive opinion about the extension of mandatory vaccines were components of the confidence, complacency and convenience dimensions of the '3Cs' model.ConclusionsIn our sample, two thirds of the French population was in favour of the extension of mandatory vaccines for children. Perception of vaccine safety and benefits were major predictors for positive and negative opinions about this new policy.

Opinion about seasonal influenza vaccination among the general population 3 years after the A(H1N1)pdm2009 influenza pandemic

OBJECTIVE

To assess the opinions of the French general population about seasonal influenza vaccination three years after the A(H1N1)pdm 09 pandemic and identify factors associated with a neutral or negative opinion about this vaccination.

STUDY DESIGN

The study was conducted using data collected from 5374 participants during the 2012/2013 season of the GrippeNet.fr study. The opinion about seasonal influenza vaccination was studied on three levels ("positive", "negative" or "neutral"). The link between the participant's characteristics and their opinion regarding the seasonal influenza vaccination were studied using a multinomial logistic regression with categorical variables. The "positive" opinion was used as the reference for identifying individuals being at risk of having a "neutral" or a "negative" opinion.

RESULTS

Among the participants, 39% reported having a positive opinion about seasonal influenza vaccine, 39% a neutral opinion, and 22% a negative opinion. Factors associated with a neutral or negative opinion were young age, low educational level, lack of contact with sick or elderly individuals, lack of treatment for a chronic disease and taking a homeopathic preventive treatment.

CONCLUSIONS

These results show that an important part of the French population does not have a positive opinion about influenza vaccination in France. Furthermore, it allows outlining the profiles of particularly reluctant individuals who could be targeted by informative campaigns.

Association between recruitment methods and attrition in Internet-based studies

Internet-based systems for epidemiological studies have advantages over traditional approaches as they can potentially recruit and monitor a wider range of individuals in a relatively inexpensive fashion. We studied the association between communication strategies used for recruitment (offline, online, face-to-face) and follow-up participation in nine Internet-based cohorts: the Influenzanet network of platforms for influenza surveillance which includes seven cohorts in seven different European countries, the Italian birth cohort Ninfea and the New Zealand birth cohort ELF. Follow-up participation varied from 43% to 89% depending on the cohort. Although there were heterogeneities among studies, participants who became aware of the study through an online communication campaign compared with those through traditional offline media seemed to have a lower follow-up participation in 8 out of 9 cohorts. There were no clear differences in participation between participants enrolled face-to-face and those enrolled through other offline strategies. An Internet-based campaign for Internet-based epidemiological studies seems to be less effective than an offline one in enrolling volunteers who keep participating in follow-up questionnaires. This suggests that even for Internet-based epidemiological studies an offline enrollment campaign would be helpful in order to achieve a higher participation proportion and limit the cohort attrition.

The representativeness of a European multi-center network for influenza-like-illness participatory surveillance

Background

The Internet is becoming more commonly used as a tool for disease surveillance. Similarly to other surveillance systems and to studies using online data collection, Internet-based surveillance will have biases in participation, affecting the generalizability of the results. Here we quantify the participation biases of Influenzanet, an ongoing European-wide network of Internet-based participatory surveillance systems for influenza-like-illness.

Methods

In 2011/2012 Influenzanet launched a standardized common framework for data collection applied to seven European countries. Influenzanet participants were compared to the general population of the participating countries to assess the representativeness of the sample in terms of a set of demographic, geographic, socio-economic and health indicators.

Results

More than 30,000 European residents registered to the system in the 2011/2012 season, and a subset of 25,481 participants were selected for this study. All age classes (10 years brackets) were represented in the cohort, including under 10 and over 70 years old. The Influenzanet population was not representative of the general population in terms of age distribution, underrepresenting the youngest and oldest age classes. The gender imbalance differed between countries. A counterbalance between gender-specific information-seeking behavior (more prominent in women) and Internet usage (with higher rates in male populations) may be at the origin of this difference. Once adjusted by demographic indicators, a similar propensity to commute was observed for each country, and the same top three transportation modes were used for six countries out of seven. Smokers were underrepresented in the majority of countries, as were individuals with diabetes; the representativeness of asthma prevalence and vaccination coverage for 65+ individuals in two successive seasons (2010/2011 and 2011/2012) varied between countries.

Conclusions

Existing demographic and national datasets allowed the quantification of the participation biases of a large cohort for influenza-like-illness surveillance in the general population. Significant differences were found between Influenzanet participants and the general population. The quantified biases need to be taken into account in the analysis of Influenzanet epidemiological studies and provide indications on populations groups that should be targeted in recruitment efforts.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2458-14-984) contains supplementary material, which is available to authorized users.

Determinants of follow-up participation in the Internet-based European influenza surveillance platform Influenzanet

BACKGROUND

"Influenzanet" is a network of Internet-based platforms aimed at collecting real-time data for influenza surveillance in several European countries. More than 30,000 European volunteers participate every year in the study, representing one of the largest existing Internet-based multicenter cohorts. Each week during the influenza season, participants are asked to report their symptoms (if any) along with a set of additional questions.

OBJECTIVE

Focusing on the first influenza season of 2011-12, when the Influenzanet system was completely harmonized within a common framework in Sweden, the United Kingdom, the Netherlands, Belgium, France, Italy, and Portugal, we investigated the propensity of users to regularly come back to the platform to provide information about their health status. Our purpose was to investigate demographic and behavioral factors associated with participation in follow-up.

METHODS

By means of a multilevel analysis, we evaluated the association between regular participation during the season and sociodemographic and behavioral characteristics as measured by a background questionnaire completed by participants on registration.

RESULTS

We found that lower participation in follow-up was associated with lower educational status (odds ratio [OR] 0.80, 95% CI 0.75-0.85), smoking (OR 0.64, 95% CI 0.59-0.70), younger age (OR ranging from 0.30, 95% CI 0.26-0.33 to 0.70, 95% CI 0.64-0.77), not being vaccinated against seasonal influenza (OR 0.77, 95% CI 0.72-0.84), and living in a household with children (OR 0.69, 95% CI 0.65-0.74). Most of these results hold when single countries are analyzed separately.

CONCLUSIONS

Given the opportunistic enrollment of self-selected volunteers in the Influenzanet study, we have investigated how sociodemographic and behavioral characteristics may be associated with follow-up participation in the Influenzanet cohort. The study described in this paper shows that, overall, the most important determinants of participation are related to education and lifestyle: smoking, lower education level, younger age, people living with children, and people who have not been vaccinated against seasonal influenza tend to have a lower participation in follow-up. Despite the cross-country variation, the main findings are similar in the different national cohorts, and indeed the results are found to be valid also when performing a single-country analysis. Differences between countries do not seem to play a crucial role in determining the factors associated with participation in follow-up.

Decreasing prolactin levels leads to a lower diving effort but does not affect breeding success in Adélie penguins

Current research on seabirds suggests a key role of hormones in the trade-off between self-maintenance and parental investment through their influence on foraging decisions during the breeding period. Although prolactin is known to have major effects on parental care, its role in foraging behavior has rarely been investigated in seabirds to date. The aim of this study was to assess the influence of an experimental decrease in prolactin levels on foraging decisions and its consequences on breeding success in free-living seabirds. To achieve this, we implanted bromocriptine (an inhibitor of prolactin secretion) in male Adélie penguins (Pygoscelis adeliae), monitored their foraging behavior using time-depth recorders over several trips, and recorded their reproductive output. On average 8±0.5days after implantation, we showed that bromocriptine administration led to an efficient decrease in prolactin levels. However, no differences were seen in foraging trip durations between bromocriptine-implanted birds and controls. Moreover, the time spent diving and the number of dives performed per trip were similar in both groups. By contrast, all diving parameters (including diving efficiency) were negatively affected by the treatment during the first at-sea trip following the treatment. Finally, the treatment did not affect adult body condition or chick growth and survival. Our study highlights the short-term negative effect of low prolactin levels on diving effort, but indicates that a short-term and/or low-magnitude decrease in prolactin levels alone is not sufficient to modify consistently the body maintenance or the parental investment of Adélie penguins.

Determination of French influenza outbreaks periods between 1985 and 2011 through a web-based Delphi method

BACKGROUND

Assessing the accuracy of influenza epidemic periods determined by statistical models is important to improve the performance of algorithms used in real-time syndromic surveillance systems. This is a difficult problem to address in the absence of a reliable gold standard. The objective of this study is to establish an expert-based determination of the start and the end of influenza epidemics in France.

METHODS

A three-round international web-based Delphi survey was proposed to 288 eligible influenza experts. Fifty-seven (20%) experts completed the three-rounds of the study. The experts were invited to indicate the starting and the ending week of influenza epidemics, on 32 time-series graphs of influenza seasons drawn using data from the French Sentinelles Network (Influenza-like illness incidence rates) and virological data from the WHO-FluNet. Twenty-six of 32 time-series graphs proposed corresponded to each of the French influenza seasons observed between 1985 and 2011. Six influenza seasons were proposed twice at each round to measure variation among expert responses.

RESULTS

We obtained consensual results for 88% (23/26) of the epidemic periods. In two or three rounds (depending on the season) answers gathered around modes, and the internal control demonstrated a good reproducibility of the answers. Virological data did not appear to have a significant impact on the answers or the level of consensus, except for a season with a major mismatch between virological and incidence data timings.

CONCLUSIONS

Thanks to this international web-based Delphi survey, we obtained reproducible, stable and consensual results for the majority of the French influenza epidemic curves analysed. The detailed curves together with the estimates from the Delphi study could be a helpful tool for assessing the performance of statistical outbreak detection methods, in order to optimize them.

Effectiveness of 2012-2013 influenza vaccine against influenza-like illness in general population: estimation in a French web-based cohort

Most of the methods used for estimating the influenza vaccine effectiveness (IVE) target the individuals who have an influenza-like illness (ILI) rather than virologically-proven influenza and access the healthcare system. The objective of this study was to estimate the 2012-2013 IVE in general French population, using a cohort of volunteers registered on GrippeNet.fr, an online surveillance system for ILI. The IVE estimations were obtained through a logistic regression, and analyses were also performed by focusing on at-risk population of severe influenza, and by varying inclusion period and ILI definition. Overall, 1996 individuals were included in the analyses. The corrected IVE was estimated to 49% (20 to 67) for the overall population, and 32% (0 to 58) for the at-risk population. Three covariables appeared with a significant effect on the occurrence of at least one ILI during the epidemic: the age (P = 0.045), the presence of a child in the household (P<10(-3)), and the frequency of cold/flu (P<10(-3)). Comparable results were found at epidemic peak time in the hypothesis of real-time feed of data. In this study, we proposed a novel, follow-up, web-based method to reveal seasonal vaccine effectiveness, which enables analysis in a portion of the population that is not tracked by the health care system in most VE studies.

Evaluating the feasibility and participants' representativeness of an online nationwide surveillance system for influenza in France

The increasing Internet coverage and the widespread use of digital devices offer the possibility to develop new digital surveillance systems potentially capable to provide important aid to epidemiological and public health monitoring and research. In France, a new nationwide surveillance system for influenza-like illness, GrippeNet.fr, was introduced since the 2011/2012 season based on an online participatory mechanism and open to the general population. We evaluate the recruitment and participation of users to the first pilot season with respect to similar efforts in Europe to assess the feasibility of establishing a participative network of surveillance in France. We further investigate the representativeness of the GrippeNet.fr population along a set of indicators on geographical, demographic, socio-economic and health aspects. Participation was widespread in the country and with rates comparable to other European countries with partnered projects running since a longer time. It was not representative of the general population in terms of age and gender, however all age classes were represented, including the older classes (65+ years old), generally less familiar with the digital world, but considered at high risk for influenza complications. Once adjusted on demographic indicators, the GrippeNet.fr population is found to be more frequently employed, with a higher education level and vaccination rate with respect to the general population. A similar propensity to commute for work to different regions was observed, and no significant difference was found for asthma and diabetes. Results show the feasibility of the system, provide indications to inform adjusted epidemic analyses, and highlight the presence of specific population groups that need to be addressed by targeted communication strategies to achieve a higher representativeness in the following seasons.