Predictors of One-Year Retention in Methadone Maintenance Treatment (MMT) in Iran, Rafsanjan

BACKGROUND Retention in treatment is a key factor to the success of methadone maintenance treatment (MMT) and considered an important measure in evaluation of treatment effectiveness. OBJECTIVES This study aimed to investigate the retention rate and predictors of retention in MMT in Rafsanjan. PATIENTS AND METHODS This was a historical cohort study. A total of 1396 patients admitted between March 2011 and March 2012 in 16 MMT clinics (13 private and 3 state clinics) in Rafsanjan, entered the study and their retention rate was examined for one year. The patients' data abstracted from their medical records using checklists and collected by clinics' staff. Data analyses were performed using SPSS 15.0 and SAS 9.1. Kaplan-Meier method and Cox proportional hazards model were used to determine the retention rate and identify predictors of retention, respectively. RESULTS The mean age of 1396 patients was 37.65 ± 10.77 years and most patients were men (93.8%). The mean and median of retention duration were 193.22 ± 3.83 and 153 ± 9.54 days, respectively. Three-month and one-year retention rates were 66.0% and 34.4%, respectively. Predictor variables of one-year retention in Cox proportional hazards model were high methadone dosage, polysubstance abuse and treatment under state clinics. CONCLUSIONS In this study, retention rate was lower compared to previous studies from other countries. The results suggested that program related factors are better predictors of retention than individual related ones.