[Factors influencing the rate on retention to methadone maintenance treatment program among heroin addicts in Guizhou, China].

To understand the situation of client-retention to methadone maintenance treatment (MMT) program and related factors. A cohort study was adopted. In total, 1003 heroin addicts who were treated at 8 local MMT clinics with less than one month period, were recruited under nominal informed consent from Guizhou province, southwest part of China, during June to October 2006. Face-to-face interview and questionnaire administered to collect relevant information from the clients who were also followed until June 2007 to understand the situation on retention. Data were analyzed with Kaplan-Meier method to estimate the retention rate at different time spans while factors related to retention were analyzed with Cox proportional hazard regression model. All the clients were followed-up for 14 months, with an average retention of ten months. The retention rates of the clients were 68.8% and 57.4% at 6th-month and 12th-month of the treatment program, estimated by Kaplan-Meier method. Results of Cox regression analysis showed that factors influencing retention rate on MMT among the clients, including their awareness on MMT, daily dose of methadone intake, and different MMT clinics which they were attached to. Risk influencing the withdrawal from MMT had a 20% decrease along with the increase when the daily dose of methadone intake reached 25 mg, with a hazard ratio of 0.80 (P < 0.01). If the clients were aware that methadone was a life-time treatment when they began the MMT program, the risk for withdrawal would be lower than those who were not and the hazard ratio became 0.66 (P < 0.05). Our data showed that about half of the clients who were at the MMT program would still stick to it after 12-months, suggesting that the retention rate was not satisfactory and need to be improved. Factors as the MMT clinics themselves that the clients visited, daily methadone dosage they took, and the awareness on MMT etc. were important predictors to the rate of retention on MMT program.