Childhood Maltreatment and Adult Multimorbidity.

Importance: Child maltreatment is a major global public health concern with well-documented psychological consequences, but its associations with long-term physical health conditions remain less well understood. Objective: To examine the associations between childhood maltreatment and adult multimorbidity using electronic health records in Hong Kong. Design, Setting, and Participants: This population-based cohort study used electronic health record data from Hong Kong, comprising 7473 individuals with a first recorded episode of maltreatment between ages 0 and 19 years from 2001 to 2010 and 26 834 matched individuals without documented maltreatment. Individuals who reached adulthood (ie, after age 19 years) by December 31, 2024, were included. Exposure: History of childhood maltreatment vs none. Main Outcomes and Measures: The primary outcome was the occurrence of multimorbidity during adulthood as documented in participants' diagnostic records through December 31, 2024. Cox proportional hazards models were used to estimate the risks of 16 disease categories and multimorbidity patterns diagnosed after age 19 years, both overall and stratified by preexisting physical, mental, or neurodevelopmental conditions in childhood. Results: After exclusions, the final cohort comprised 32 674 individuals (16 986 female [52%]), including 7137 who were exposed to childhood maltreatment and 25 537 unexposed individuals. Their median (IQR) age was 9.0 (6.0-13.0) years at inclusion and 28.1 (24.2-31.6) years at the end of follow-up. The median (IQR) follow-up duration was 19.0 (16.6-21.3) years. Childhood maltreatment was associated with increased risks across 13 adult diagnostic categories. The highest risks were observed with mental and behavioral disorders (hazard ratio [HR], 2.78; 95% CI, 2.49-3.09), ear diseases (HR, 1.88; 95% CI, 1.27-2.78), injuries (HR, 1.81; 95% CI, 1.65-1.98), and blood diseases (HR, 1.67; 95% CI, 1.41-1.97). Maltreatment was also associated with a higher risk and earlier onset of complex multimorbidity (HR, 1.96; 95% CI, 1.68-2.27). The associations between childhood maltreatment and adult diagnoses were attenuated among individuals with mental health or neurodevelopmental conditions diagnosed in childhood. Conclusions and Relevance: In this 19-year cohort study of 32 674 individuals, childhood maltreatment was associated with elevated risks for multiple health conditions in adulthood. These findings underscore the need for early prevention and sustained, trauma-informed health care support to reduce the risk of lifelong multimorbidity among children who have experienced maltreatment.