Sylvie Boyer

Associate faculty ,  INSERM

Boyer
Status
Assistant professor
Research domain(s)
Health economics
Thesis
2010, Aix-Marseille Université
Contact
sylvie.boyer[at]inserm.fr
Abstract Introduction: Expanding health insurance is viewed as a core strategy for achieving universal health coverage. In Senegal, as in many other developing countries, this strategy has been implemented by creating community-based health insurance (CBHI) schemes with voluntary enrolment and a fixed premium paid by enrollees. Yet little is known about how the individuals’ experience of CBHI enrolment further influences their willingness to pay (WTP). In this paper, we test the existence of a reinforcement effect between effective enrolment in a CBHI and WTP for health insurance by analysing their mutual relationship. Methods: We rely on primary survey data collected in 2019–2020 in the rural area of Niakhar in Senegal. We use an econometric methodology involving: (1) Heckman-type selection models to estimate the determinants of CBHI membership conditioned on awareness of health insurance, addressing the issue of sample selection due to differential awareness and (2) a simultaneous equation model to jointly estimate the uptake and WTP for health insurance, addressing the issue of endogeneity due to reverse causality between both variables. We also focus on the roles that informational and geographical barriers, as well as individual risk preference and trust, play in both outcomes. Results: The final sample includes 1607 individuals. Results show that WTP further increases with the individuals’ direct experience in a CBHI scheme, despite an environment characterised by low enrolment rates. We also provide evidence for a U‐shaped relationship between risk tolerance and WTP for health insurance. Conclusion: We provide novel evidence on a reinforcement effect of enrolment in a CBHI on WTP for health insurance, with the presence of a substantial consumer surplus among enrolled individuals at the actual premium. Our findings suggest that policies aiming at improving health insurance awareness should foster the demand for health insurance in rural Senegal.
Keywords Health insurance, Community-based health insurance, Uptake, Willingness to pay, Information, Rural health, Rural population, Senegal, Sub-Saharan Africa
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Abstract Abstract This paper investigates linkage to care following community‐based screening for hepatitis B virus (HBV) in rural Senegal. HBV‐positive participants who completed a biological and clinical examination to assess liver disease and treatment eligibility were referred to a regional hospital (if eligible for treatment), invited to join the Sen‐B research cohort study (adults with detectable viral load) or referred to their local health centre (all others). Logistic regressions were conducted to investigate factors associated with (i) uptake of the scheduled post‐screening examination, and (ii) HBV management initiation. Obstacles to HBV management were identified using thematic analysis of in‐depth patient interviews. Of the 206 HBV‐positive participants, 163 (79.1%) underwent the examination; 47 of the 163 (28.8%) initiated HBV management. Women, people not migrating for >6 months/year, individuals living in households with more agricultural and monetary resources, with other HBV‐positive participants, and beneficiaries of the national cash transfer program, were all more likely to undergo the examination. The likelihood of joining the Sen‐B cohort increased with household monetary resources, but decreased with agricultural resources. Initiation of HBV management in local health centre was higher among participants with a non‐agricultural economic activity. Individuals reported wariness and confusion about HBV management content and rationale at various stages of the care continuum, in particular with respect to venous blood sampling and management without treatment. In conclusion, HBV community‐based test‐and‐treat strategies are feasible, but early loss to follow‐up must be addressed through simplified, affordable management and community support and sensitization.
Keywords Hepatitis B surface antigen, Adjusted odds-ratios, DBS, Dried blood spots, XOF, WHO, World Health Organization, SSA, Sub-Saharan Africa, PwHBV, People living with HBV, IQR, Interquartile range, HDSS, Health and Demographic Surveillance System, HBV, Hepatitis B virus, HBsAg, Confidence interval DBS, CI, Confidence interval, Senegal, Chronic hepatitis B virus HBV infection, Linkage to care, AOR, Adjusted odds-ratios CI, West African franc, Dried blood spots HBsAg, Hepatitis B surface antigen HBV, Hepatitis B virus HDSS, Health and Demographic Surveillance System IQR, Interquartile range pwHBV, People living with HBV sSA, Sub-Saharan Africa WHO, World Health Organization XOF
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Abstract 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.
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Abstract 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.
Keywords Rural, Senegal, Chronic hepatitis B, Social justice mixed-methods study, Health capability profile, Health capability model
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Abstract 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 awarenessbased 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 decisionmakers 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.
Keywords Sub-Saharan Africa, Senegal, Selection bias, Risk preference, Health insurance, Geographic distance, Awareness
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Abstract 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.
Keywords Child, Hepatitis B, Prevalence, Risk factors, Senegal
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Abstract 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.
Keywords Vaccination coverage, Vaccination timeliness, Senegal, Pentavalent vaccination, Hepatitis B vaccine, Birth dose vaccination
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Abstract 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.
Keywords Infectious diseases, Health outcomes, Value, Specialist care, Referrals
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Abstract Point-of-care (POC) laboratories that deliver rapid diagnoses of ă infectious diseases were invented to balance the centralization of core ă laboratories. POC laboratories operate 24 h a day and 7 days a week to ă provide diagnoses within 2 h, largely based on immunochromatography and ă real-time PCR tests. In our experience, these tests are conveniently ă combined into syndrome-based kits that facilitate sampling, including ă self-sampling and test operations, as POC laboratories can be operated ă by trained operators who are not necessarily biologists. POC ă laboratories are a way of easily providing clinical microbiology testing ă for populations distant from laboratories in developing and developed ă countries and on ships. Modern Internet connections enable support from ă core laboratories. The cost-effectiveness of POC laboratories has been ă established for the rapid diagnosis of tuberculosis and sexually ă transmitted infections in both developed and developing countries.
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Abstract Direct out-of-pocket payments for health care continue to be a major source of health financing in low- and middle-income countries. Some of these direct payments take the form of informal charges paid by patients to access the needed health care services. Remarkably, however, little is known about the extent to which these payments are exercised and their determinants in the context of Sub-Saharan Africa. This study attempts therefore to shed light on the role of supply-side factors in the occurrence of informal payments while accounting for the demand-side factors. The study relies on data taken from a nationally representative survey conducted among people living with HIV/AIDS in Cameroon. A multilevel mixed-effects logistic model is employed to identify the factors associated with the incidence of informal payments. Results reveal that circa 3.05% of the surveyed patients incurred informal payments for the consultations made on the day of the survey. The amount paid informally represents up to four times the official tariff. Factors related to: (i) human resources management of the health facilities (e.g., task shifting); (ii) health professionals’ perceptions vis-à-vis the remunerations of HIV-care provision and (iii) reception of patients (e.g., waiting time) significantly influence the probability of incurring informal payments. Also of note, the type of health care facilities is found to play a role: informal payments appear to be significantly lower in private non-profit facilities compared to those belonging to public sector. Our findings allude to some policy recommendations than can help reduce the incidence of informal payments.
Keywords Economie quantitative
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