Association Between Substance Use and Injury Risk: A 10-Year Nationwide Retrospective Cohort Study

Objective: This study aimed to investigate the association between substance use and the risk of developing injuries. Methods: This retrospective cohort study analyzed data from a national health database between 2013 and 2022, including 324,648 individuals with documented substance use and an equal number of matched controls. Substance types included alcohol, drugs, tobacco, and other substances. Injuries were classified into six subtypes: suicide, intentional injury, vehicle-related injury, falls, fire-related injury, and drowning. Cox proportional hazards models were used to assess injury risk, adjusting for sociodemographic and clinical variables. Kaplan-Meier survival curves were used to assess cumulative injury risk over time. Results: Substance users had a significantly higher risk of injury compared to non-users (adjusted hazard ratio [aHR] = 1.444, p < 0.001). The greatest risks were observed for suicide (aHR = 10.287), intentional injury (aHR = 2.453), and falls (aHR = 1.742). Drug use was most strongly associated with suicide and intentional injury, while alcohol use showed a strong association with fall and vehicle-related injuries. Other substances presented the highest injury risks across several subtypes. Additional risk factors included female gender, low income, major illness, comorbidities (stroke, diabetes, hypertension, hyperlipidemia), and high urbanization levels. Kaplan-Meier curves revealed that the cumulative injury risk for substance users diverged significantly from non-users beginning around year two and continued to increase over the 10-year follow-up period. Conclusion: Substance use significantly increases injury risk across multiple injury types, with varying impacts depending on the substance involved. These findings underscore the importance of targeted interventions and prevention strategies that address substance-specific risks and vulnerable populations.