Intravenous opiate maintenance in a cohort of injecting drug addicts

Drug addiction is a major problem in many societies. The opiate maintenance program includes a prospective cohort of injecting drug addicts, treated with opiates such as heroin intravenously. An important aim of this program is to keep patients under medical supervision in order to reduce the health hazards associated with illicit drug consumption. In this paper we report the performance of this drug policy in terms of retention and analyse treatment withdrawals and hospitalisations.

Treatment retention was assessed using the Kaplan-Meier method (treatment withdrawals were defined as the event of interest). We analysed factors associated with treatment withdrawal using Cox regression analysis. In addition, we analysed hospitalisations occurring during the study period.

Of 175 patients included in the study, 76 withdrew from the study. Of these, 29 were transferred to a substitution program. The 3-year probability of remaining in the study was 61.7% (95%CI: 54.8-69.4%). Risk of treatment withdrawal was independently associated with age (hazard ratio 0.88 [95%CI: 0.82-0.95]) and years of intravenous drug use (hazard ratio 1.11 [95%CI: 1.04-1.18]). No association was found between risk of treatment withdrawal and HIV-, Hepatitis B Virus (HBV) or Hepatitis C Virus (HCV) serostatus. The percentages of HIV, HBV and HCV seroconversions observed during the study period were 0.7, 16.2 and 23.3%, respectively. A total of 84 hospitalisations were recorded in 49 patients, mainly due to infectious diseases. Hospitalised patients were not more likely to withdraw from the program.

Retention is high in the intravenous opiate maintenance program and favours the continuation of this drug policy. Individuals with a shorter history of injecting drug use and of older age are more likely to continue intravenous opiate maintenance treatment.