| BackgroundNumber of illegal drug users in China has increased rapidly in recent years. At present, sharing syringes and needles among injection drug users (IDUs) is a major route of transmission of human immunodeficiency virus (HIV) in China. Prevalence of drug addiction interweaves with HIV infection epidemic, leading more challenges for the prevention and control of acquired immune deficiency syndrome (AIDS). In order to effectively contain spread of HIV in IDUs, community-based methadone maintenance treatment (MMT) for them was initiated in early 2004 in China. It is a key indicator for guaranteeing and evaluating the effectiveness of MMT that if the clients can adhere to the treatment.AimsTo understand baseline demographic characteristics of the clients in MMT, to identify related factors for their retention in MMT, and to evaluate the effectiveness of MMT, including changes in their addiction severity.Study methodsA cohort design was used in this study. Heroin addicts who were primarily treated in one of the eight MMT clinics in Guizhou Province were recruited into the cohort with informed consent from June to October 2006. Baseline data from the clients were collected with an ad-hoc questionnaire including addiction severity index of Chinese version (ASI-C) by face to face interview. They were followed-up six months after MMT to evaluate its effectiveness. Retention rate in MMT of the clients was estimated by Kaplan-Meier method and factors influencing their retention were analyzed by proportional hazard (Cox) regression model. Difference in retention rates for varied groups was compared with lag-rank test.ResultsA total of 1 003 MMT clients were enrolled from eight MMT clinics into the study and 470 of them were followed-up for six months.1. Demographic characteristics of the clients in MMTAverage age of 1 003 participants was 33.3 years, 86.6 percent under 35 years, 26.0 percent women, 64.6 percent with junior high school education or below and 49.6 percent unmarried, and 70.5 percent of them got living support from their families or relatives. About half of the participants (52.0 percent) were IDUs with 23.2 percent sharing needles, 7.1 percent with more than one sexual partners, 81.7 percent and 67.4 percent of them with psychiatric and psychological problems prior to the MMT and during the past 30 days, respectively, but only 3.8 percent of them treated. Each of the clients took 38.1mg of methadone per day in average.2. Retention in MMT of the clients and its related factorsThe study lasted for 14 months and the clients were treated for 10 months in average. Retention rate in the 1 003 clients was 68.8 percent, 57.4 percent and 56.2 percent in the 6th month, 12th month and 14th month of MMT, respectively, estimated by Kaplan-Meier method. About 43 percent of the clients withdrew from MMT in the 12th month of treatment. Main factors influencing retention of the clients in MMT included their awareness of MMT, daily dose of methadone they took, and varied MMT clinics they visited. Risk for withdrawal from MMT decreased by 20 percent with increase in daily dose of methadone 25mg, with a hazard ratio of 0.80 (P<0. 01). If the clients understood that they should take methadone life-time as they entered MMT program, their risk for withdrawal would be lower than those who did not understand, with a hazard ratio of 0.66 (P<0. 05). The highest retention rate was seen in the MMT clinic at Anshun County and the lowest at Panxian County.3. Effectiveness of MMTAddiction severity index of the clients significantly decreased after six-month MMT, and scores of six domains in ASI-C, i.e., physical health, employment, drug addiction, legal status, family and social status, and psychiatric status, all significantly declined, as compared to those at baseline (P<0.01). 4. Clients continued heroin use during MMTAbout 30 percent of the clients were positive for urine morphine during the first 10 months of MMT, suggesting they continued to use heroin, and then positive rate of urine morphine decreased obviously to about 20 percent by the 11th month and to less than four percent by the end of the 14th month.5. Reliability and validity of addiction severity index of Chinese versionPilot study and verification study indicated a good internal consistency of composite scores of ASI-C, with an average Cronbach's alpha greater than 0.60, as an acceptable level overall. Pilot study in 35 clients, in general showed good enough test-retest reliability of the composite scores (CSs) of ASI-C with an interval of seven days. All the seven domains were extracted from the ASI-C by factor analysis in verification study, consistent with those in construct validity of the original version of ASI.ConclusionsThe clients participated in MMT in Guizhou were younger, less educated, and with a little bit larger proportion of women than those in other provinces. About half of the participants could retain in MMT after 14-month treatment. Different MMT clinics the clients visited, daily methadone dose, and their awareness of MMT were main predictors of retention in MMT. MMT was significantly effective with six-month retention, but more concerns should be attached to those clients who continued to use heroin during the treatment. Reliability and validity of ASI-C available is fundamentally acceptable, but further modification is needed based on culture in China.
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