Global burden and inequalities of drug use disorders from 1990 to 2021 with projections to 2036

The COVID-19 pandemic further exacerbated the burden of drug use disorders (DUDs), and systematic quantification of inequalities in DUDs remains limited. Thus, a comprehensive evaluation of the global burden and inequalities of DUDs following the COVID-19 pandemic is necessary.

We used data from the Global Burden of Disease 2021 study to evaluate the global burden of DUDs from 1990 to 2021, stratified by sex, age, country, region, socio-demographic index (SDI), and drug category. The slope index of inequality and the concentration index of inequality are applied to quantify absolute and relative inequalities in both overall and drug-specific burdens across SDI regions. Future trends through 2036 were projected using an autoregressive integrated moving average model and Bayesian age-period-cohort model.

This study revealed that the global burden of DUDs increased greatly from 1990 to 2021, with the highest burden observed among individuals aged 15-49 years and consistently greater in males. High-income North America and the USA bore the highest burden at the regional and national levels, respectively. The analysis by drug category indicated that opioid use disorder represented the predominant contributor to the overall burden of DUDs. Both absolute and relative inequalities in the overall burden of DUDs increased across SDI levels, with marked variations in inequality patterns across drug categories. Inequalities have intensified for opioid and amphetamine use disorders, whereas those related to cannabis use disorders have declined. Both models predicted increasing incidence, deaths, and age-standardised mortality rate accompanied by declining age-standardised prevalence rate, but showed opposite trends for prevalence, disability-adjusted life years (DALYs), age-standardised incidence rate, and age-standardised DALY rate.

Over the past three decades, the burden of DUDs has increased markedly, accompanied by wide disparities. Addressing these challenges requires strengthened surveillance, context-specific interventions, and cross-country learning.