Opiate maintenance with buprenorphine in ambulatory care: a 24-week follow-up study of new users.

BACKGROUND: Many studies suggest that buprenorphine, a long acting partial opioid agonist, may be comparable to methadone in efficacy, with fewer withdrawal symptoms and a lower risk of overdose. The aim of this study was to assess the patterns of buprenorphine prescription use in ambulatory care and retention rate under treatment during a 24-week follow-up period. METHODS: This observational cohort study included buprenorphine users identified from the French Health System prescription database in an area of 1 million inhabitants and followed for 24 weeks. RESULTS: We selected 282 users of buprenorphine defined as "new users" (74% male, mean age 32.4+/-6.2 years). Three groups were defined: 50% of "rational users" (141 subjects, no more than 2 prescribers), 24% of "occasional users" (67 subjects, less than 2 buprenorphine prescriptions) and 26% of "non-rational users" (74 subjects, 3 or more prescribers). The overall 24-week treatment retention rate was 37%. Misuse of buprenorphine or benzodiazepines was significantly more frequent in "non-rational" than "rational users". CONCLUSION: The retention rate with buprenorphine estimated in this observational study was very similar to that obtained in controlled trials. A majority of regular users of buprenorphine could be regarded as "rational users" in this area of France.