Participation and population characteristics
Of the 20,032 individuals included in the 2016-HB, 17,781 were eligible for BaroTest and were invited to receive the home-sampling testing kit (Figure 1). Of the 12,944 (72.8%) who agreed to participate, 6,945 persons (53.7%) returned the DBS with the signed informed consent form to the NRC, representing 39.1% of all those initially invited to participate.
The characteristics of BaroTest participants and non-participants and 2016-HB participants are presented in Tables 1-2. Before BaroTest weighting, BaroTest participants (column 3) differed significantly from non-participants (column 4) for all socio-demographical characteristics, except gender. With regard to HCV and HBV risk exposure, BaroTest participants did not differ from non-participants, except for exposures related to country of birth (Table 2). Furthermore, BaroTest participants reported HBV (p=0.03) or HIV (p<10-3) screening and vaccination against HBV (p<10-3) more frequently than non-participants.
After BaroTest weighting, the distributions of the main socio-demographical characteristics of BaroTest participants (column 2) were similar to those in the national population.
With regard to risk exposure factors, 6.3% of BaroTest participants reported a blood transfusion before 1992, 0.6% intravenous (IV) drug use in their lifetime, 12.6% health care or a prolonged stay in Africa, Asia or the Middle East, 4.3% household or sexual contact with an HBV-infected person, 2.1% a tattoo or a piercing made without single-use materials, and 1.3% a sexually transmitted infection (STI, excluding mycosis) in the previous 12 months. Finally, 3.8% of male participants declared having sex with men during their lifetime.
CHC and CHB prevalence estimates
HCV RNA was detected in 11 individuals. CHC prevalence in the general population aged 18-75 living in mainland France was estimated at 0.30% (95% Confidence interval (CI):0.13-0.70), corresponding to 133,466 individuals (95% CI: 56,880-312,616). The prevalence did not significantly differ between men (0.34%) and women (0.26%) (Table 3). CHC prevalence was significantly higher in persons: i) 46-75 years old (0.51%) than those 18-45 years old (0.08%, p<0.05), ii) with an educational level lower than secondary school certificate (0.52%) than those with a higher diploma (0.08%, p<10-2) and iii) with a household monthly income in the lowest tercile (0.74%) than those living in a household with a monthly income in the 2nd or the 3rd terciles (0.07%, p<10-3). With regard to HCV risk exposure factors, CHC prevalence reached 12.1% among those who reported IV drug use in their lifetime (vs. 0.24% for those reporting no drug use, p<10-3) and was significantly higher in those with a tattoo or piercing not made with single-use materials than in others (2.55% vs. 0.25%, p<10-2). CHC prevalence was not significantly higher in persons with a history of blood transfusion before 1992 (1.12%) than in those without such a history (0.24%).
Among persons with CHC, 80.6% (95% CI: 44.2-95.6) were estimated to be aware of their infection, corresponding to 107,574 (95% CI: 58,992-127,594) people aged 18-75 years in the general population in mainland France.
Among the 6,945 persons tested for HBsAg, 18 were positive. CHB prevalence in the general population aged 18-75 years living in mainland France was estimated at 0.30% (95% CI: 0.13-0.70), corresponding to 135,706 people (95% CI: 58,224-313,960). CHB prevalence did not significantly differ between men (0.28%) and women (0.32%) (Table 3). Prevalence was significantly higher in persons: i) aged 46-75 years (0.51%) than in those aged 18-45 years (0.10%, p<0.05), ii) in those with the lowest tercile of household monthly income (0.63%) than in those in the 2nd or 3rd terciles (0.14%, p<0.05) and iii) among persons who benefited from specific health insurance for low-income persons (CMU: Complementary Universal Health Insurance or AME: State Medical Insurance for irregular migrants) (1.98%) than those who did not benefit from CMU or AME (0.16%, p<10-3). CHB prevalence was associated with place of birth (p<10-3), reaching 5.81% in persons born in Sub-saharan Africa compared with 0.14% in persons born in mainland France. CHB prevalence was estimated at 3.39% in men who reported at least one male sexual partner in their lifetime (vs. 0.16% in men who did not, p<10-3). CHB prevalence was not significantly higher in persons who reported STI (1.16%) than in those with no history of STI in the previous 12 months (0.30%).
Among those with CHB, an estimated 17.5% (95% CI: 4.9-46.4) were aware of their infection, corresponding to 23,749 (95% CI: 6,650-62,967) persons aged 18-75 years in the general population in mainland France.
HCV and HBV screening history
Among the participants in 2016-HB, 19.2% (95% CI: 18.6-19.9) and 35.6% (95% CI: 34.8-36.5) reported at least one test for HCV and HBV during their lifetime, respectively (Table 2). In multivariate analysis, the likelihood of a HCV and HBV screening history increased with educational level (Table 4). A history of screening for HCV or HBV was more frequently reported by participants living in the Paris urban area or in a city with at least 100,000 inhabitants than by those living in rural areas, and more frequently reported by those benefiting from CMU or AME than those who did not. HCV or HBV screening history was reported more frequently by participants with the following HCV or HBV exposure risks: lifetime drug use, healthcare or prolonged stay in countries with high endemicity for HCV or HBV, blood transfusion before 1992, household or sexual contact with an HBV infected person, lifetime sexual relations with men for male participants, and an STI in the previous 12 months.
Participants aged 61-75 years old were less likely to report HCV screening than those in the 15-30 years old age group, whereas for HBV, those in the 31-45 and 46-60 years old age groups more frequently reported screening than the 15-30 years old age group. A history of HBV testing was more frequent in participants reporting HBV vaccination. All these results remained unchanged when stratifying for sex.
In total, 32.6 % (95% CI: 31.7-33.4) of 2016-HB participants reported that they had never been screened for HCV, HBV or HIV during their lifetime, while 85.3% (95% CI: 84.7-85.9) either reported that they had never been screened for any of the viruses or that they had been screened for only one or two viruses. This corresponds to a minimal estimate of 15,380,061 (95% CI: 14,955,458-15,757,485) and a maximal estimate of 40,242,919 (95% CI: 39,959,851-40,525,988) persons aged of 15-75 years in the general population of mainland France that would need to be screened if the proposed “universal combined screening” strategy were implemented.