BackgroundEpidemiology of HCV infection among drug users (DUs) has been widely studied. Prevalence and sociobehavioural data among DUs are therefore available in most countries but no study has taken into account in the sampling weights one important aspect of the way of life of DUs, namely that they can use one or more specialized services during the study period. In 2004–2005, we conducted a national seroepidemiologic survey of DUs, based on a random sampling design using the Generalised Weight Share Method (GWSM) and on blood testing.MethodsA cross-sectional multicenter survey was done among DUs having injected or snorted drugs at least once in their life. We conducted a two stage random survey of DUs selected to represent the diversity of drug use. The fact that DUs can use more than one structure during the study period has an impact on their inclusion probabilities. To calculate a correct sampling weight, we used the GWSM. A sociobehavioral questionnaire was administered by interviewers. Selected DUs were asked to self-collect a fingerprick blood sample on blotting paper.ResultsOf all DUs selected, 1462 (75%) accepted to participate. HCV seroprevalence was 59.8% [95% CI: 50.7–68.3]. Of DUs under 30 years, 28% were HCV seropositive. Of HCV-infected DUs, 27% were unaware of their status. In the month prior to interview, 13% of DUs shared a syringe, 38% other injection parapharnelia and 81% shared a crack pipe. In multivariate analysis, factors independently associated with HCV seropositivity were age over 30, HIV seropositivity, having ever injected drugs, opiate substitution treatment (OST), crack use, and precarious housing.ConclusionThis is the first time that blood testing combined to GWSM is applied to a DUs population, which improve the estimate of HCV prevalence. HCV seroprevalence is high, indeed by the youngest DUs. And a large proportion of DUs are not aware of their status. Our multivariate analysis identifies risk factors such as crack consumption and unstable housing.

In France a harm-reduction policy was implemented in the late 1980s with the aim of reducing the prevalence of HIV and hepatitis C virus (HCV) infection among drug users. The ANRS-Coquelicot survey was designed to measure the prevalence of HIV and HCV infection among drug users and to examine determinants of at-risk behaviors. In 2002, information was collected from 166 drug users recruited in all types of services specializing in drug use intervention and harm reduction in Marseille, France. Self-reported HIV and HCV serostatus was compared with the results of serological tests done on capillary blood collected on filter paper. The self-reported and biologically documented prevalence rates of HIV infection were identical (22%). In contrast, the self-reported prevalence of HCV infection was 52%, whereas the biologically documented prevalence was 73%. Overall, 30% of HCV-infected drug users were unaware of their status. Forty-four percent of drug users under 30 years of age were HCV seropositive, suggesting that they had been infected early during drug use. The harm-reduction policy seems to have had a marked impact on HIV transmission among drug users but a much more limited impact on HCV transmission. The limitations and implications of the study are discussed.

No abstract

No abstract

Since the mid-1990s, Time-Location Sampling methods have been widely used in France in quantitative research about the homeless (Marpsat and Firdion, 2000; Brousse, 2002) and drug users (Emmanuelli et al. 2003;Jauffret-Roustide et al. 2006). Adapted from methods of indirect sampling initially developed in the United States (Burt and Cohen, 1989;Dennis and Iachan, 1993), they enable the design of representative samples of hard-to-reach populations for whom there are no sample frames, by basing it on support facilities for the populations of interest: day centres, soup kitchens, accommodation services, health care, mobile teams etc. However, in transition from the theoretical protocol to its implementation, various difficulties emerge. In particular, the necessary involvement of these support services; the constraints associated with the administering of questionnaires in sometimes very particular conditions (at night, in public places or while following mobile teams) and the singular organisation of each of the services that has to be involved means that challenges occur as regards coverage of the field being investigated and the representativeness of the sample. These challenges mean that the method has to be appropriately and pragmatically adapted to the various configurations that are met with. In this perspective, we will show how the integration of qualitative methods, such as the observation of the services and the realisation of in-depth interviews with the persons in charge of them, have contributed, along the various data collections and with the accumulation of experiences, to improve the methodology of and the scope covered by quantitative surveys.