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

AimsTo 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. DesignPopulation-based treatment cohort study. SettingLinked mortality data on all individuals first enrolled in publicly funded pharmacological treatment for opioid dependence in California, USA from 2006 to 2010. ParticipantsA 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). MeasurementsThe primary outcome was mortality, indicated by time to death, crude mortality rates (CMR) and standardized mortality ratios (SMR). FindingsIndividuals 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. ConclusionsIn people with opiate dependence, detoxification and methadone maintenance treatment both independently reduce the instantaneous hazard of all-cause and drug-related mortality.