Global adolescent self-harm (10–19 years): 1990–2021 trends, health inequalities, frontier analysis, and 2035 projections using global burden of disease data

Objectives: Adolescent self-harm is a major global health concern, yet evidence focused specifically on those aged 10-19 years remains limited. This study comprehensively assessed its global burden. Methods: Using data from the Global Burden of Disease Study 2021, we analyzed trends in incidence, years lived with disability (YLDs), disability-adjusted life years (DALYs), and risk factors from 1990 to 2021, and projected trends to 2035. Frontier analysis, health inequality assessment, and autoregressive integrated moving average (ARIMA) models were applied, and average annual percent change (AAPC) was estimated for 204 countries and territories. Results: In 2021, the global incidence of adolescent self-harm was 66.75 per 100,000 (95% CI: 43.34 to 97.12). Females showed 1.85-fold and 1.82-fold higher incidence and YLDs rates than males, while males had 1.16-fold higher DALYs rates. Greenland ranked highest across all three rates. From 1990 to 2021, incidence, YLDs, and DALYs rates declined in absolute terms, yet 91 countries exhibited increasing AAPC values (relative rise). The incidence and YLDs rates were significantly associated with the socio-demographic index (SDI), while DALYs were not. The Slope Index of Inequality decreased to -17.74, reflecting a growing concentration of burden in low-SDI settings, whereas some high-SDI settings showed persistent health-efficiency gaps. The population attributable fractions of high alcohol use and high temperature increased to 2.82 and 2.80%, respectively. Forecasts suggest declining incidence and DALYs rates but a rising YLDs rates by 2035. Conclusion: Nearly half of all countries show rising trends in adolescent self-harm incidence, with burdens shifting toward non-fatal outcomes and low-SDI settings, underscoring the need for gender-sensitive, equity-focused, and prevention-oriented global strategies to guide future self-harm intervention policies.