Mortality among individuals accessing pharmacological treatment for opioid dependence in California, 2006-10

Aims: To estimate mortality rates among treated opioid-dependent individuals by cause and in relation to the general population, and to estimate the instantaneous effects of opioid detoxification and maintenance treatment (MMT) on the hazard of all-cause and cause-specific mortality. Design: Population-based treatment cohort study. Setting: Linked mortality data on all individuals first enrolled in publicly funded pharmacological treatment for opioid dependence in California, USA from 2006 to 2010. Participants: A total of 32322 individuals, among whom there were 1031 deaths (3.2%) over a median follow-up of 2.6 years (interquartile range=1.4-3.7). Measurements: The primary outcome was mortality, indicated by time to death, crude mortality rates (CMR) and standardized mortality ratios (SMR). Findings: Individuals being treated for opioid dependence had a more than fourfold increase of mortality risk compared with the general population [SMR=4.5, 95% confidence interval (CI)=4.2, 4.8]. Mortality risk was higher (1) when individuals were out-of-treatment (SMR=6.1, 95% CI=5.7, 6.5) than in-treatment (SMR=1.8, 95% CI=1.6, 2.1) and (2) during detoxification (SMR=2.4, 95% CI=1.5, 3.8) than during MMT (SMR=1.8, 95% CI=1.5, 2.1), especially in the 2weeks post-treatment entry (SMR=5.5, 95% CI=2.7, 9.8 versus SMR=2.5, 95% CI=1.7, 4.9). Detoxification and MMT both independently reduced the instantaneous hazard of all-cause and drug-related mortality. MMT preceded by detoxification was associated with lower all-cause and other cause-specific mortality than MMT alone. Conclusions: In people with opiate dependence, detoxification and methadone maintenance treatment both independently reduce the instantaneous hazard of all-cause and drug-related mortality.