Global, regional, and national trends in drug use disorder mortality rates across 73 countries from 1990 to 2021, with projections up to 2040: a global time-series analysis and modelling study.

Background: Drug use disorder (DUD) poses a major public health crisis globally, necessitating immediate attention to global trends and future projections to develop effective health policies and interventions. Thus, we aimed to estimate the global trends in DUD mortality rates from 1990 to 2021 and future projections of DUD deaths until 2040 across 73 countries. Methods: In this time-series analysis and modelling study, we investigated the global trends in DUD mortality rates from 1990 to 2021 using the WHO Mortality Database and forecasted future trends through 2040. Global trend analysis was analysed using a locally weighted scatter plot smoother (LOESS) curve, and future projections were calculated based on a Bayesian age-period-cohort analysis. In addition, we performed a decomposition analysis to identify the variations in DUD deaths, specifically examining factors such as population growth, ageing, and epidemiological changes. Findings: Of the 73 countries included in the analysis of DUD mortality, 45 were high-income countries (HICs), and 28 were low to middle-income countries (LMICs). The LOESS estimates of the global DUD mortality rate were 1.84 deaths per 1,000,000 people (95% CI, -0.44 to 4.12) in 1990 and 13.09 deaths per 1,000,000 people (95% CI, 10.74-15.43) in 2021. Notably, HICs showed a significant increase in DUD mortality from 1.43 deaths per 1,000,000 people (95% CI, -1.55 to 4.42) in 1990 to 17.19 deaths per 1,000,000 people (95% CI, 13.84-20.53) in 2021. A significant increase in DUD mortality was observed among individuals aged 25-64 and males. Our analysis also identified associations between DUD mortality rates and several log-transformed parameters, including Human Development Index (β, 14.92; p < 0.0001), Socio-demographic Index (β, 11.80; p < 0.0001), reverse Gender Gap Index (β, -12.02; p < 0.0001), and Gini coefficient (β, -1.84; p < 0.0001). From 1990 to 2021, the increase in the number of DUD deaths globally can be attributed to two prominent factors: epidemiological change and population growth. In HICs, the impacts of epidemiological changes for increasing DUD mortality rates were particularly prominent compared to other factors. In the Bayesian age-period-cohort models, the predicted number of global DUD deaths up to 2040 were estimated to increase from 25.95 deaths per 1,000,000 people (95% credible interval [CrI], 24.72-27.28) in 2021 to 38.45 (95% CrI, 30.48-49.33) in 2030, and 42.43 (95% CrI, 23.67-77.77) in 2040. Interpretation: An increasing trend in global DUD mortality was observed from 1990 to 2021, especially in HICs. Future DUD deaths were also predicted to increase until 2040 at the global level. Therefore, these findings suggest urgent and proactive strategies for DUD to reduce the mortality rates related to DUD are needed. However, further prospective research that accounts for potential confounding factors, such as socioeconomic variables and the quality of reporting data from individual countries, is imperative for more accurate estimation. Funding: National Research Foundation and Ministry of Science and ICT of South Korea.