Retention and its predictors among methadone maintenance treatment clients in China: a six-year cohort study

Abstract

Background: To investigate factors associated with retention among the first cohort of drug users attending methadone maintenance treatment (MMT) clinics in China.

Methods: A six-year cohort of 1511 drug users was enrolled in the first 8 MMT clinics in China in 2004 and followed between March, 2004 and December, 2010. Six-year retention rates were calculated and compared by methadone dosage, clinic location, and length of follow-up. Factors associated with retention were evaluated using Cox proportional hazard regression models.

Results: The overall retention rate over 6-year was 35.7%. Highest drop-out occurred within the first 12 months of treatment. The retention rates for the 6-year by low (≤ 30 mg/day), medium (31-60 mg/day), and high (>60 mg/day) methadone dosage groups were 20.8%, 34.8% and 53.2%, respectively (p < 0.001). The highest 6-year retention rate among eight clinics was 43.8%, while the lowest one was 17.7% (p < 0.001). The results from Cox proportional hazard models indicate that clients having >30 mg daily methadone dosage (p < 0.001), having relatives receiving MMT (p = 0.027), and having >10% urine morphine positive result (p < 0.001) were more likely to be retained in MMT over the six-year period. It has also found that drug injection (p = 0.005) and needle sharing (p < 0.0001) were significantly associated with better retention.

Conclusions: Health workers should adjust individuals' methadone dosages as a method to prevent early treatment termination. Further studies are needed to explore the impact of severity of opiate addiction on long-term retention of MMT clients. Careful assessment of drug users upon MMT enrollment may be helpful for providing additional care to clients.

Keywords: Cohort study; Methadone maintenance treatment; Retention; Risk factor.