Factors associated with injection cessation, relapse and initiation in a community-based cohort of injection drug users in Chennai, India

Aims To characterize factors associated with injection cessation, relapse and initiation. Design The Madras Injection Drug User and AIDS Cohort Study (MIDACS) is a prospective cohort of injection drug users (IDUs) recruited in 2005-06 with semi-annual follow-up to 2009. Discrete-time survival models were used to characterize predictors of time to first injection cessation and relapse. Setting Chennai, India. Participants A total of 855 IDUs who reported injecting in the 6 months prior to baseline and had >1 follow-up visit. Measurements Cessation was defined as the first visit where no injection drug use was reported (prior 6 months) and relapse as the first visit where drug injection (prior 6 months) was reported after first cessation. Findings All participants were male; median age was 35 years. Over 3 years, 92.7% reported cessation [incidence rate (IR): 117 per 100 person-years]. Factors associated positively with cessation included daily injection and incarceration and factors associated negatively with cessation included marriage, alcohol and homelessness. Of those who reported cessation, 23.6% relapsed (IR: 19.7 per 100 person-years). Factors associated positively with relapse included any education, injection in the month prior to baseline, sex with a casual partner, non-injection drug use, incarceration and homelessness. Alcohol was associated negatively with relapse. The primary reasons for cessation were medical conditions (37%) and family pressure (22%). The majority initiated with non-injection drugs, transitioning to injection after a median 4 years. Conclusions Injection drug users in southern India demonstrate a high rate of injection cessation over 3 years, but relapse is not uncommon. Compensatory increases in alcohol use indicate that cessation of injection does not mean cessation of all substance use. Family pressure, concerns about general health, fear of human immunodeficiency virus infection and a history of non-injection drug use are important correlates of cessation.