Illicit drug use and injection practices among drug users on methadone and buprenorphine maintenance treatment in France.

Aims: To evaluate the associations between methadone and high-dose buprenorphine maintenance treatment and illicit drug use and injection among drug users in France.

Design: A cross-sectional study. Data were gathered using a questionnaire administered containing closed-ended questions.

Setting: Drug dependence clinics (DDC) and general practitioners' (GPs) offices in three French cities.

Participants: Drug users undergoing maintenance treatment with methadone (n = 197) and buprenorphine (n = 142).

Measurements: Interviews covered the use of illicit drugs (heroin, cocaine or crack) and injection practices (illicit drugs and/or substitution drugs) during the last month, current treatment modalities, socio-demographic and health characteristics. Bivariate analysis and multivariate logistic regressions were conducted.

Findings: Overall, 35.4% of respondents (34.5% in the methadone group, 36.6% in the buprenorphine group, P= 0.69) had used at least one illicit drug, 25.7% reported having injected drugs and 15.3% had injected the substitution drug. Injection was more common among buprenorphine-maintained individuals (40.1%) than among users on methadone (15.2%) (P < 0.01). Multivariate analyses indicate that the type of substitution drug (buprenorphine versus methadone) was not associated with illicit drug use (OR = 1.1; 95% CI = 0.7-1.8). In the buprenorphine group, injection was related independently to social situation, as measured by housing (unstable versus stable housing, OR = 4.3; 95% CI = 1.6-11.5), but this was not the case in the methadone group. The risk of injection increased with buprenorphine dosage (high/low dosage OR = 6.2; 95% CI = 2.0-19.7), but this association was not observed in the methadone group.

Conclusion: Further studies comparing the benefits of these two types of treatment should be carried out, taking outcomes such as physical health, mental health and social functioning into consideration.