Mortality among a cohort of drug users after their release from prison: an evaluation of the effectiveness of a harm reduction program in Taiwan

Aims To determine the effect of methadone maintenance therapy (MMT) on mortality among injection drug users. Design A cohort of prisoners with a history of injecting opiates who were followed after their release from prison in July 2007. Mortality between July 2007 and December 2008 was determined by linking the National Death Registry with the Methadone Maintenance Treatment (MMT) database. Setting Taiwan. Participants A total of 4357 amnestied prisoners with a history of opiate injection. Measurements The total mortality rates (MR) among the cohort were calculated based on their person-time contribution to methadone attendance and re-incarceration during follow-up. We used survival methods with MMT and re-incarceration as time-varying covariates adjusted for length of follow-up in the community. Results A total of 142 deaths occurred: 13 in the 1st week after release [MR = 13.7/100 person-years (pyrs)], which was greater than that in the next 4 weeks [MR = 3.2/100 pyrs, relative rate (RR) = 4.3, P < 0.001]. Overall, 1982 (46%) subjects enrolled in MMT; however, 1282 of them discontinued MMT after enrolling. Findings The mortality among those who continued in MMT attendance was lower (MR = 0.24/100 pyrs) than those who never enrolled in MMT (MR = 2.6/100 pyrs) or those who enrolled but dropped out of MMT (MR = 7.0/100 pyrs) after adjusting for age, gender and human immunodeficiency virus status at amnesty (RR = 0.07). Conclusions In ex-prisoners in Taiwan with a history of opiate injecting, enrollment and continued participation in methadone maintenance treatment is associated with substantially lower mortality.