Drug abuse-associated mortality across the lifespan: a population-based longitudinal cohort and co-relative analysis

Nationwide data have been lacking on drug abuse (DA)-associated mortality. We do not know the degree to which this excess mortality results from the characteristics of drug-abusing individuals or from the effects of DA itself.

DA was assessed from medical, criminal, and prescribed drug registries. Relative pairs discordant for DA were obtained from the Multi-Generation and Twin Registers. Mortality was obtained from the Swedish Mortality registry.

We examined all individuals born in Sweden 1955-1980 (n = 2,696,253), 75,061 of whom developed DA. The mortality hazard ratio (mHR) (95% CIs) for DA was 11.36 (95% CIs, 11.07-11.66), substantially higher in non-medical (18.15, 17.51-18.82) than medical causes (8.05, 7.77-8.35) and stronger in women (12.13, 11.52-12.77) than in men (11.14, 10.82-11.47). Comorbid smoking and alcohol use disorder explained only a small proportion of the excess DA-associated mortality. Co-relative analyses demonstrated substantial familial confounding in the DA-mortality association with the strongest direct effects seen in middle and late-middle ages. The mHR was highest for opiate abusers (24.57, 23.46-25.73), followed by sedatives (14.19, 13.11-15.36), cocaine/stimulants (12.01, 11.36-12.69), and cannabis (10.93, 9.94-12.03).

The association between registry-ascertained DA and premature mortality is very strong and results from both non-medical and medical causes. This excess mortality arises both indirectly-from characteristics of drug-abusing persons-and directly from the effects of DA. Excess mortality of opiate abuse was substantially higher than that observed for all other drug classes. These results have implications for interventions seeking to reduce the large burden of DA-associated premature mortality.