Examination of mortality rates in a retrospective cohort of patients treated with oral or implant naltrexone for problematic opiate use

AIMS: To examine and compare mortality rates in patients treated with oral and implant naltrexone. DESIGN: A retrospective cohort study. SETTING: A community not-for-profit drug treatment clinic. PARTICIPANTS: Patients treated with oral naltrexone (n = 2155, 17 207 patient-years) and implant naltrexone (n = 2389, 11 678 patient-years) for problematic opiate use between August 1997 and December 2009. MEASUREMENTS: Crude gender, age, treatment period and cause-specific mortality rates were calculated using data obtained from the National Death Index. FINDINGS: Crude mortality rates for patients treated with oral naltrexone [8.78 deaths per 1000 patient-years (ptpy), 95% confidence interval (CI): 7.38-10.17] were significantly different to those treated with implant naltrexone (6.59 ptpy, 95% CI: 5.13-8.06) (P = 0.0339). During the first 4 months following treatment, differences in the two groups were particularly apparent, with a mortality rate of 26.28 ptpy in patients treated with oral naltrexone compared to 7.34 ptpy in patients treated with implant naltrexone (P = 0.0003). Differences in initial mortality rates following treatment were associated predominantly with high rates of opiate overdoses in oral naltrexone patients during the first 4 months following treatment (17.22 ptpy compared with 0.67 ptpy in implant naltrexone patients) (P < 0.0001). CONCLUSIONS: The use of implant naltrexone can reduce all-cause mortality and opiate overdose during the first 4 months following treatment compared with patients treated with oral naltrexone.