Exposure to opioid maintenance treatment reduces long-term mortality

Abstract

Aims: To (i) examine the predictors of mortality in a randomized study of methadone versus buprenorphine maintenance treatment; (ii) compare the survival experience of the randomized subject groups; and (iii) describe the causes of death.

Design: Ten-year longitudinal follow-up of mortality among participants in a randomized trial of methadone versus buprenorphine maintenance treatment.

Setting: Recruitment through three clinics for a randomized trial of buprenorphine versus methadone maintenance.

Participants: A total of 405 heroin-dependent (DSM-IV) participants aged 18 years and above who consented to participate in original study.

Measurements: Baseline data from original randomized study; dates and causes of death through data linkage with Births, Deaths and Marriages registries; and longitudinal treatment exposure via State health departments. Predictors of mortality examined through survival analysis.

Findings: There was an overall mortality rate of 8.84 deaths per 1000 person-years of follow-up and causes of death were comparable with the literature. Increased exposure to episodes of opioid treatment longer than 7 days reduced the risk of mortality; there was no differential mortality among methadone versus buprenorphine participants. More dependent, heavier users of heroin at baseline had a lower risk of death, and also higher exposure to opioid treatment. Older participants randomized to buprenorphine treatment had significantly improved survival. Aboriginal or Torres Strait Islander participants had a higher risk of death.

Conclusions: Increased exposure to opioid maintenance treatment reduces the risk of death in opioid-dependent people. There was no differential reduction between buprenorphine and methadone. Previous studies suggesting differential effects may have been affected by biases in patient selection.