Retention and outcomes for clients attending a methadone clinic in a resource-constrained setting: a mixed methods prospective cohort study in Imphal, Northeast India

Background Opioid substitution therapy (OST) with buprenorphine has been widely available in India since 2007, but the introduction of methadone occurred much later in 2012, and availability remains limited. Illicit injecting drug use is a long-standing public health problem in Manipur, a state in Northeast India characterised by major resource constraints and political unrest. We investigated retention and outcomes for clients attending a methadone-based OST program in Manipur with the aim of strengthening the evidence base for development of relevant policies and programs. Methods All clients enrolling in the methadone clinic over a 1 year period were invited to be part of a prospective cohort study, which followed up and surveyed both retained and defaulting clients for 12 months post-enrollment to assess retention as well as social, behavioural and mental health outcomes. Additionally, we conducted semi-structured qualitative interviews to supplement quantitative information and identify factors contributing to retention and drop-out. Results Of the 74 clients enrolled, 21 had dropped out and three had died (all defaulters) by 12 months post-enrollment, leaving 67.6% still in the program. Using an intention-to-treat analysis, meaningful and statistically significant gains were observed for all social, behavioural and mental health variables. Between baseline and 12 months there were reductions in needle sharing, drug use, property crime, anxiety, depression and suicidal thoughts; and improvements in physical health, mental health, quality of family relationships, employment and hopefulness. Factors contributing to retention and drop-out were identified, including the centrality of family, and general lack of awareness of and misunderstanding about methadone. Conclusion Even in parts of India where resources are constrained, methadone is an effective treatment for opioid dependence. Scaling up the availability of methadone elsewhere in Manipur and in other areas of India experiencing problematic opioid dependence is indicated.