Mortality and causes of death among persons with alcohol use disorder only versus persons with opioid dependence: results from a 19-year prospective cohort study.

Background: Substance use disorders (SUD) are associated with increased mortality. Mortality risk is highest among people with opioid use disorder (OUD) while alcohol use disorder (AUD) has the greatest impact on population mortality due to its great prevalence. However, mortality risk and causes of death between OUD versus AUD patients have rarely been studied within the same cohort. Here we compare these phenomena among people with AUD only and people with OUD within the same cohort.

Methods: Design: Prospective cohort study. Setting: Norway. Sample: 131 persons with AUD only, who received specialist SUD treatment in 1998 and 200 OUD patients who entered opioid agonist treatment (OAT, within specialized SUD treatment) for the first time as of 1998 until 2007, totally 331 persons, in Innlandet county, Norway. Observation period: Individual study entry: AUD group 1 Jan 1998, OAT group the 15th the month they started OAT. End point: time of death or Dec 31 2016. Statistics: Causes of death, descriptive. Mortality risk, Cox regression model with covariates baseline age/sex. Data sources: Hospital records, The Norwegian Cause of Death Registry.

Results: 66 (50%) in the AUD-group versus 41 (21%) in the OAT-group died during the study. Causes of death were categorised as somatic disease ('natural'), drug-induced (fatal overdose/SUD as death cause), traumatic (accident, suicide, homicide), 4) unknown. Distribution (AUD/OUD): somatic disease 58%/54%, drug-induced 27%/27%, traumatic 11%/15%. Mortality risk adjusted for SUD-group (OAT reference): Hazard ratio (HR) 1.97 (95% CI 1.32–2.96), p=0.001. HR adjusted for SUD-group, sex, age: SUD-group (OAT reference) 0.91(0.54–1.53), p=0,723, sex (female reference) 2.15 (1.28–3.62), p=0,004, age (per year) 1.05 (1.03–1.08), p=0.000.

Conclusion: In this clinical cohort of patients with severe AUD/OUD the distribution of causes of death and mortality risk adjusted for sex and baseline age was equal between AUD only and OAT patients.