Long-Term Trends in Self-Harm Mortality Across the World’s Countries: Associations with Human Development, Democracy, and Income Inequality

Abstract

Introduction: Self-harm mortality remains a public health concern. Monitoring long-term trends across countries informs prevention strategies. Aim: To examine global trends in self-harm mortality rates (SHMR) from 1990 to 2023 and determine whether countries followed distinct trajectories according to socioeconomic characteristics. Methods: Age-standardized SHMRs for 204 countries were obtained from the Global Burden of Disease Study. Latent Growth Models estimated temporal trends and compared trajectories according to Human Development Index (HDI), democratic governance (V-Dem), and income inequality (Gini). Exploratory Growth Mixture Modeling (GMM) identified latent classes of countries with similar longitudinal trajectories. Results: Global SHMR declined significantly between 1990 and 2023 (b = −0.074/year, p < .001), with the steepest reductions observed in Europe and Central Asia. Countries classified as having higher HDI and lower income inequality exhibited significantly steeper declines in SHMR, whereas differences according to democratic governance were not statistically significant. Sensitivity analyses using timevarying socioeconomic indicators showed that annual HDI became increasingly associated with lower SHMR over time, whereas annual Gini and V-Dem had limited or inconsistent associations, with the declining SHMR trend remaining robust after adjustment for Gini and V-Dem. GMM identified three distinct trajectory classes characterized by low, intermediate, and high baseline SHMR with corresponding gradual, moderate, and steep declines. Conclusions: Global SHMR declined substantially over the study period but followed heterogeneous trajectories across countries. Countries classified by higher human development and lower income inequality exhibited steeper historical declines in SHMR, while GMM suggested that regional and historical contexts also contributed to long-term trajectory differences.