Risk factors for leaving treatment among heroin addicts: results from the Italian national cohort study VEdeTTE, 1998-2001

Background Retention in treatment has been showed to improve opioid addicts’ health; an increasing interest of the research is to identify the factors which contribute to retention in order to improve the effectiveness of treatments. Aim To identify risk factors for leaving treatments among heroin addicts in Italy. Methods All methadone maintenance and residential treatments running through the first 6 months of the study were included in the analysis. Patients were enrolled in 115 treatments centres in Italy. 6286 methadone maintenance treatments and 1208 residential programmes were analysed as regards the risk of leaving treatment, using Cox proportional hazards models. Variables included: patients’ age, sex, family situation, employment status, education level, past legal problems, length of heroin use, previous treatments and failures, frequency of injection, cocaine, alcohol and psychoactive drugs use, needle/tools sharing, HIV/HBV/HCV status, methadone dose, concurrent psychotherapy, psychiatric diagnosis, treatment centres characteristics. Results Younger age at the enrolment, unemployment, unstable family situation, past legal problems, enrolment place, previous methadone treatments and previous failures, needle/tools sharing, HIV/HBV/HCV negative status and psychiatric diagnosis were strongly related with an increased risk of leaving methadone maintenance treatment. Methadone dosage and additional psychosocial treatments were powerful determinants of retention, HR of leaving treatment ranging from 1.00 for doses lower than 40 mg/day to 0.42 for doses higher than 110 mg/day, and from 1.00 for no additional treatments to 0.33 for psychotherapy. Past legal problems, concurrent methadone treatment, previous residential treatments and needle/tools sharing were associated with an increased risk of leaving residential treatment. Conclusions This analysis supports the findings of previous studies, that unstable leaving conditions, risk behaviours, previous failures and low dose of methadone increase the risk of leaving methadone programs. Because of the protective effect of retention in treatment on drug use, mortality, sero-conversion and social-reintegration of drug addicts, high dosage policies are strongly recommended.