Effectiveness of Methadone Maintenance Therapy and Improvement in Quality of Life Following a Decade of Implementation

• Methadone maintenance therapy is effective in improving several outcome domains.
• Quality of life improved with methadone treatment.
• Quality of life does not further improve as duration of methadone treatment increased.
• Age above 50 years old, positive HIV status and physical symptoms predicted a poorer improvement in quality of life.

Methadone maintenance therapy has been found to be an effective harm reduction treatment for opioid use disorder. However evidence of its benefits over a longer duration of treatment is limited as most studies focus on its short term benefits. As methadone maintenance therapy reaches a decade since its implementation in Malaysia, this study sought to examine the effectiveness of methadone treatment, change in quality of life among patients since entry to methadone treatment, as well as factors predicting the magnitude of change in quality of life. This study found that methadone maintenance therapy was effective in reducing heroin use, injecting practices and crime, and in improving in social functioning and physical symptoms, but not in reducing sex-related HIV risk-taking behavior. Though patients had a significantly better quality of life at follow-up than at entry to methadone maintenance therapy, the improvement in quality of life was not significantly greater as the duration of treatment increased. Age above 50 years old, human immunodeficiency virus (HIV) positive status and physical symptoms predicted a poorer improvement in quality of life between baseline and follow-up. On the other hand, patients with hepatitis B showed a greater improvement in quality of life in the social relationships domain compared to patients without hepatitis B. In conclusion, methadone maintenance therapy is an effective treatment for opioid use disorder and improves quality of life but its benefits in further improving quality of life beyond a decade of treatment need further evaluation.