Medication Nonadherence and Risk of Violence to Others Among Patients With Schizophrenia in Western China.

Importance: Reducing violence to others in community-based patients with schizophrenia has important implications for public health. Increasing medication adherence is often used to reduce the risk of violence, yet little is known about the association between medication nonadherence and violence to others in this population. Objective: To examine the association between medication nonadherence and violence to others among community-based patients with schizophrenia. Design, Setting, and Participants: This large, naturalistic, prospective cohort study was performed in western China from May 1, 2006, to December 31, 2018. The data set was from the integrated management information platform for severe mental disorders. As of December 31, 2018, 292 667 patients with schizophrenia were registered in the platform. During follow-up, patients could enter or leave the cohort at any time. Maximum follow-up was 12.8 years, with a mean (SD) of 4.2 (2.3) years. Data analysis was conducted from July 1, 2021, to September 30, 2022. Exposures: Medication nonadherence. Main Outcomes and Measures: Violence to others throughout the follow-up period was the outcome, including minor nuisances, violating the Law of the People's Republic of China on Penalties for Administration of Public Security (APS law), and violating criminal law. Information about these behaviors was provided by the public security department. Directed acyclic graphs were used to identify and control confounders. Propensity score matching and generalized linear mixed-effects models were used for analysis. Results: The final study sample included 207 569 patients with schizophrenia. The mean (SD) age was 51.3 (14.5) years, and 107 271 (51.7%) were women; 27 698 (13.3%) perpetrated violence to others, including 22 312 of 142 394 with medication nonadherence (15.7%) and 5386 of 65 175 with adherence (8.3%). In 112 710 propensity score-matched cases, risks of minor nuisances (odds ratio [OR], 1.82 [95% CI, 1.75-1.90]; P < .001), violating APS law (OR, 1.91 [95% CI, 1.78-2.05]; P < .001), and violating criminal law (OR, 1.50 [95% CI, 1.33-1.71]; P < .001) were higher in patients with nonadherence. However, the risk did not increase with higher medication nonadherence. There were differences in risk of violating APS law between urban and rural areas. Conclusions and Relevance: Medication nonadherence was associated with a higher risk of violence to others among community-based patients with schizophrenia, but the risk did not increase as medication nonadherence increased.