Boyer

Publications

Hepatitis B prevention and treatment needs in women in Senegal (ANRS 12356 AmBASS survey)Journal articleTchadine Djaogol, Lauren Perieres, Fabienne Marcellin, Assane Diouf, Maria Patrizia Carrieri, Aldiouma Diallo, Sylvie Boyer, Cyril Bérenger, Marwan al Qays Bousmah, Morgane Bureau, et al., BMC Public Health, Volume 23, Issue 1, pp. 825, 2023

Background:
Although mother-to-child transmission (MTCT) of hepatitis B virus (HBV) is prevalent in West Africa, epidemiological data on HBV infection in women remain scarce. We studied i) hepatitis B surface antigen (HBsAg) prevalence and its correlates, ii) HBV screening history and serological status awareness, iii) MTCT risk and treatment needs in Senegalese women.

Methods:
A cross-sectional population-based serosurvey for HBsAg positivity was conducted in 2018–2019 in the rural area of Niakhar (Fatick region, Senegal). Participants were offered home-based HBV screening and answered face-to-face questionnaires. HBsAg-positive participants underwent clinical and biological assessments. Data were weighted and calibrated to be representative of the area’s population. Logistic regression models helped identify factors associated with HBsAg-positivity in adult women (> 15 years old).

Results:
HBsAg prevalence in adult women was 9.2% [95% confidence interval: 7.0–11.4]. Factors associated with HBsAg-positivity were being 15–49 years old (ref: ≥ 50), living in a household with > 2 other HBsAg-positive members, and knowing someone with liver disease. Only 1.6% of women had already been tested for HBV; no one who tested HBsAg positive was already aware of their serological status. In women 15–49 years old, 5% risked MTCT and none were eligible for long-term antiviral treatment.

Conclusions:
Adult women have a high HBsAg prevalence but a low MTCT risk. Low rates of HBV screening and serological status awareness argue for the adoption of systematic screening during pregnancy using free and rapid diagnostic tests. Additionally, screening household members of HBsAg-positive women may greatly improve the cascade of care in rural Senegal.

Rethinking the management of chronic hepatitis B in the context of rural sub-saharan Africa: results from a social justice mixed methods study in rural Senegal (the AmBASS-PeCSen study)Journal articleMarion Coste, Cilor Ndong, Aldiouma Diallo, Assane Diouf, Sylvie Boyer et Jennifer Prah, Journal of Hepatology, Volume 77, pp. S202-S203, 2022
Hepatitis B in Senegal: A Successful Infant Vaccination Program but Urgent Need to Scale Up Screening and Treatment (ANRS 12356 AmBASS survey)Journal articleLauren Perieres, Aldiouma Diallo, Fabienne Marcellin, Marie Libérée Nishimwe, El Hadji Ba, Marion Coste, Gora Lo, Philippe Halfon, Coumba Toure Kane, Gwenaelle Maradan, et al., Hepatology Communications, Volume 6, Issue 5, pp. 1005-1015, 2022

Senegal introduced the infant hepatitis B virus (HBV) vaccination in 2004 and recently committed to eliminating hepatitis B by 2030. Updated epidemiological data are needed to provide information on the progress being made and to develop new interventions. We estimated the prevalence of hepatitis B surface antigen (HBsAg) in children and adults living in rural Senegal and assessed hepatitis B treatment eligibility. A cross-sectional population-based serosurvey of HBsAg was conducted in 2018-2019 in a large sample (n = 3,118) of residents living in the Niakhar area (Fatick region, Senegal). Individuals positive for HBsAg subsequently underwent clinical and biological assessments. Data were weighted for age and sex and calibrated to be representative of the area's population. Among the 3,118 participants, 206 were HBsAg positive (prevalence, 6.9%; 95% confidence interval [CI], 5.6-8.1). Prevalence varied markedly according to age group in individuals aged 0-4, 5-14, 15-34, and >= 35 years as follows: 0.0% (95% CI, 0.00-0.01); 1.5% (95% CI, 0.0-2.3); 12.4% (95% CI, 9.1-15.6); and 8.8% (95% CI, 6.1-11.5), respectively. Of those subsequently assessed, 50.9% (95% CI, 41.8-60.0) had active HBV infection; 4 (2.9%; 95% CI, 0.9-9.4) were eligible for hepatitis B treatment. Conclusion: In this first population-based serosurvey targeting children and adults in rural Senegal, HBsAg prevalence was very low in the former, meeting the World Health Organization's (WHO) < 1% HBsAg 2020 target; however, it was high in young adults (15-34 years old) born before the HBV vaccine was introduced in 2004. To reach national and WHO hepatitis elimination goals, general population testing (particularly for adolescents and young adults), care, and treatment scale-up need to be implemented.

Hepatitis B in Senegal: A Successful Infant Vaccination Program but Urgent Need to Scale Up Screening and Treatment (ANRS 12356 AmBASS survey)Journal articleLauren Perieres, Aldiouma Diallo, Fabienne Marcellin, Marie Libérée Nishimwe, El Hadji Ba, Marion Coste, Gora Lo, Philippe Halfon, Coumba Toure Kane, Gwenaelle Maradan, et al., Hepatology Communications, Volume 6, Issue 5, pp. 1005-1015, 2022

Senegal introduced the infant hepatitis B virus (HBV) vaccination in 2004 and recently committed to eliminating hepatitis B by 2030. Updated epidemiological data are needed to provide information on the progress being made and to develop new interventions. We estimated the prevalence of hepatitis B surface antigen (HBsAg) in children and adults living in rural Senegal and assessed hepatitis B treatment eligibility. A cross-sectional population-based serosurvey of HBsAg was conducted in 2018-2019 in a large sample (n = 3,118) of residents living in the Niakhar area (Fatick region, Senegal). Individuals positive for HBsAg subsequently underwent clinical and biological assessments. Data were weighted for age and sex and calibrated to be representative of the area's population. Among the 3,118 participants, 206 were HBsAg positive (prevalence, 6.9%; 95% confidence interval [CI], 5.6-8.1). Prevalence varied markedly according to age group in individuals aged 0-4, 5-14, 15-34, and >= 35 years as follows: 0.0% (95% CI, 0.00-0.01); 1.5% (95% CI, 0.0-2.3); 12.4% (95% CI, 9.1-15.6); and 8.8% (95% CI, 6.1-11.5), respectively. Of those subsequently assessed, 50.9% (95% CI, 41.8-60.0) had active HBV infection; 4 (2.9%; 95% CI, 0.9-9.4) were eligible for hepatitis B treatment. Conclusion: In this first population-based serosurvey targeting children and adults in rural Senegal, HBsAg prevalence was very low in the former, meeting the World Health Organization's (WHO) < 1% HBsAg 2020 target; however, it was high in young adults (15-34 years old) born before the HBV vaccine was introduced in 2004. To reach national and WHO hepatitis elimination goals, general population testing (particularly for adolescents and young adults), care, and treatment scale-up need to be implemented.

Applying the health capability profile to empirically study chronic hepatitis B in rural Senegal: a social justice mixed-methods study protocolJournal articleMarion Coste, Mouhamed Ahmed Badji, Aldiouma Diallo, Marion Mora, Sylvie Boyer et Jennifer J. Prah, BMJ Open, Volume 12, Issue 4, pp. e055957, 2022

Introduction:
Despite the early implementation of hepatitis B vaccination and the ongoing decentralisation of chronic hepatitis B (CHB) care, over 10% of the Senegalese adult population lives with CHB and liver cancer remains a main cause of death. Investigating factors associated with CHB infection, prevention of CHB-related morbidity, and prevention and treatment of mortality secondary to CHB calls for a holistic and multidimensional approach. This paper presents the adaptation of the health capability profile (HCP) to a specific epidemiological issue and empirical setting: it seeks to identify and analyse inter-related abilities and conditions (health capabilities) in relation to the CHB epidemic in the rural area of Niakhar, Senegal.
Methods and analysis:
This ongoing study relies on a sequential social justice mixed-methods design. The HCP is comprehensively adapted to CHB in rural Senegal and guides the design and conduct of the study. Objective and subjective data are collected at the individual level following a mixed-methods explanatory core design. The quantitative module, embedded in the ANRS12356 AmBASS cross-sectional survey (exhaustive sampling), is used to select a purposeful sampling of participants invited for one-on-one qualitative interviews. Additional data are collected at the institutional and community level through health facility surveys and an ethnography (in-depth interviews) of local and national CHB stakeholders. Data analysis adopts a synergistic approach to produce a multilayered analysis of individual HCPs and crosscutting analysis of the 15 health capabilities. The data integration strategy relies on a mixed-methods convergent core design, and will use 0–100 health capability scores as well as flow diagrams to measure and characterise levels of development and interactions among health capabilities, respectively.
Ethics and dissemination:
This study was approved by Senegalese and French authorities. Results dissemination through local workshops and scientific publications aim at fuelling effective policy change towards CHB-related health capability.

Reassessing the demand for community-based health insurance in rural Senegal: Geographic distance and awarenessJournal articleMârwan-al-Qays Bousmah, Sylvie Boyer, Richard Lalou et Bruno Ventelou, SSM - Population Health, Volume 16, pp. 100974, 2021

Limited access to information is one of the main health insurance market imperfections in developing countries. Differential access to information may determine individuals’ awareness of health insurance schemes, thereby influencing their probability of enrollment. Relying on primary data collected in 2019–2020 in rural Senegal, we estimate the uptake of community-based health insurance using a Heckman-type model to correct for awareness-based sample selection bias. Besides showing that health insurance awareness is a precondition for effective enrollment in community-based health insurance schemes, we also bring new evidence on the roles which geographic factors and individual risk preference play in health insurance uptake by rural dwellers. We show that geographic distance prevents individuals from accessing information on health insurance schemes, and discourage those who are informed from enrolling, because of the additional distance they must travel to benefit from covered healthcare services. Results also show that individual risk preference influences health insurance uptake, but only when information barriers are taken into account. Overall, our results could help decision-makers better shape the universal health coverage roadmap, as policies to improve health insurance awareness differ substantially from policies to improve the features of health insurance schemes.

Sibling status, home birth, tattoos and stitches are risk factors for chronic hepatitis B virus infection in Senegalese children: A cross-sectional surveyJournal articleLauren Perieres, Camelia Protopopescu, Gora Lo, Fabienne Marcellin, El Hadji Ba, Marion Coste, Coumba Toure Kane, Aldiouma Diallo, Cheikh Sokhna, Sylvie Boyer, et al., Journal of Viral Hepatitis, Volume 28, Issue 11, pp. 1515-1525, 2021

Sub-Saharan Africa's hepatitis B virus (HBV) burden is primarily due to infection in infancy. However, data on chronic HBV infection prevalence and associated risk factors in children born post-HBV vaccination introduction are scarce. We estimated hepatitis B surface antigen (HBsAg) prevalence and risk factors in Senegalese children born during the HBV vaccination era. In 2018–2019, a community-based cross-sectional survey was conducted in Senegal among children born between 2004 and 2015 (ie after the three-dose HBV vaccine series was introduced (2004) but before the birth dose's introduction (2016)). HBsAg-positive children were identified using dried blood spots. A standardized questionnaire collected socioeconomic information. Data were age-sex weighted and calibrated to be representative of children living in the study area. Risk factors associated with HBsAg positivity were identified using negative binomial regression. Among 1,327 children, 17 were HBsAg-positive (prevalence = 1.23% (95% confidence interval [CI] 0.61–1.85)). Older age (adjusted incidence-rate ratio [aIRR] 1.31 per one-year increase, 95% CI 1.10–1.57), home vs healthcare facility delivery (aIRR 3.55, 95% CI 1.39–9.02), stitches (lifetime) (aIRR 4.79; 95% CI 1.84–12.39), tattoos (aIRR 8.97, 95% CI 1.01–79.11) and having an HBsAg-positive sibling with the same mother (aIRR 3.05, 95% CI 1.09–8.57) were all independently associated with HBsAg positivity. The low HBsAg prevalence highlights the success of the Senegalese HBV vaccination program. To further reduce HBV acquisition in children, high-risk groups, including pregnant women and siblings of HBsAg-positive individuals, must be screened. Vital HBV infection prevention measures include promoting delivery in healthcare facilities, and increasing awareness of prevention and control procedures.

Hepatitis B Vaccination in Senegalese Children: Coverage, Timeliness, and Sociodemographic Determinants of Non-Adherence to Immunisation Schedules (ANRS 12356 AmBASS Survey)Journal articleLauren Perieres, Fabienne Marcellin, Gora Lo, Camelia Protopopescu, El Hadji Ba, Marion Coste, Coumba Toure Kane, Gwenaelle Maradan, Aldiouma Diallo, Cheikh Sokhna, et al., Vaccines, Volume 9, Issue 5, pp. 510, 2021

Detailed knowledge about hepatitis B virus (HBV) vaccination coverage and timeliness for sub-Saharan Africa is scarce. We used data from a community-based cross-sectional survey conducted in 2018–2019 in the area of Niakhar, Senegal, to estimate coverage, timeliness, and factors associated with non-adherence to the World Health Organisation-recommended vaccination schedules in children born in 2016 (year of the birth dose (BD) introduction in Senegal) and 2017–2018. Vaccination status was assessed from vaccination cards, surveillance data, and healthcare post vaccination records. Among 241 children with available data, for 2016 and 2017–2018, respectively, 31.0% and 66.8% received the BD within 24 h of birth (BD schedule), and 24.3% and 53.7% received the BD plus at least two pentavalent vaccine doses within the recommended timeframes (three-dose schedule). In logistic regression models, home birth, dry season birth, and birth in 2016 were all associated with non-adherence to the recommended BD and three-dose schedules. Living over three kilometres from the nearest healthcare post, being the firstborn, and living in an agriculturally poorer household were only associated with non-adherence to the three-dose schedule. The substantial proportion of children not vaccinated according to recommended schedules highlights the importance of considering vaccination timeliness when evaluating vaccination programme effectiveness. Outreach vaccination activities and incentives to bring children born at home to healthcare facilities within 24 h of birth, must be strengthened to improve timely HBV vaccination.

The value of specialist care—infectious disease specialist referrals—why and for whom? A retrospective cohort study in a French tertiary hospitalJournal articleManoj Sasikumar, Sylvie Boyer, Anne Remacle-Bonnet, Bruno Ventelou et Philippe Brouqui, European Journal of Clinical Microbiology & Infectious Diseases, Volume 36, Issue 4, pp. 625-633, 2017

This study evaluated the impact of infectious disease (ID) specialist referrals on outcomes in a tertiary hospital in France. This study tackled methodological constraints (selection bias, endogeneity) using instrumental variables (IV) methods in order to obtain a quasi-experimental design. In addition, we investigated whether certain characteristics of patients have a bearing on the impact of the intervention. We used the payments database and ID department files to obtain data for adults admitted with an ID diagnosis in the North Hospital, Marseille from 2012 to 2014. Comparable cohorts were obtained using coarsened exact matching and analysed using IV models. Mortality, readmissions, cost (payer perspective) and length of stay (LoS) were analysed. We recorded 15,393 (85.97%) stays, of which 2,159 (14.03%) benefited from IDP consultations. The intervention was seen to significantly lower the risk of inpatient mortality (marginal effect (M.E) = –19.06%) and cost of stay (average treatment effect (ATE) = – €5,573.39). The intervention group was seen to have a longer LoS (ATE = +4.95 days). The intervention conferred a higher reduction in mortality and cost for stays that experienced ICU care (mortality: odds ratio (OR) =0.09, M.E cost = –8,328.84 €) or had a higher severity of illness (mortality: OR=0.35, M.E cost = –1,331.92 €) and for patients aged between 50 and 65 years (mortality: OR=0.28, M.E cost = -874.78 €). This study shows that ID referrals are associated with lower risk of inpatient mortality and cost of stay, especially when targeted to certain subgroups.

The Point-of-Care Laboratory in Clinical MicrobiologyJournal articleMichel Drancourt, Audrey Michel-Lepage, Sylvie Boyer et Didier Raoult, Clinical Microbiology Reviews, Volume 29, Issue 3, pp. 429-447, 2016

Point-of-care (POC) laboratories that deliver rapid diagnoses of infectious diseases were invented to balance the centralization of core laboratories. POC laboratories operate 24 h a day and 7 days a week to provide diagnoses within 2 h, largely based on immunochromatography and real-time PCR tests. In our experience, these tests are conveniently combined into syndrome-based kits that facilitate sampling, including self-sampling and test operations, as POC laboratories can be operated by trained operators who are not necessarily biologists. POC laboratories are a way of easily providing clinical microbiology testing for populations distant from laboratories in developing and developed countries and on ships. Modern Internet connections enable support from core laboratories. The cost-effectiveness of POC laboratories has been established for the rapid diagnosis of tuberculosis and sexually transmitted infections in both developed and developing countries.