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Incidence and Risk Factors of Self-harm among Patients with Schizophrenia in Taiwan: A 12-year Retrospective Cohort Study

Chia-Hao Ma, I-Ming Chen, Shih-Cheng Liao, Ming H. Hsieh, Susan Shur-Fen Gau, Ming-Been Lee, Chi-Shin Wu

Objectives: Patients with schizophrenia have higher risk of self-harm and suicide. Previous reviews revealed that previous self-harm, depressive symptoms, and substance abuse increase self-harm risk, but the incidence of self-harm of patients with schizophrenia in Taiwan has rarely been reported. In this study, we intended to explore the incidence, the self-harm methods, associated comorbidities, and socio-demographic factors. Methods: We used National Health Insurance Research Database. We included subjects who had at least two ambulatory claims or one admission with diagnosis of schizophrenia-spectrum disorder and at least one antipsychotic agent prescription during 2001-2012. Excluded were those who were too young or too old at diagnosis, diagnosed before 2001, and having missing data. We also recruited age- and sex-matched comparison group. The outcome was defi ned as the fi rst hospitalization, emergency department visits, or outpatient visits due to self-harm. Results: Patients with schizophrenia were in higher risk of history of self-harm, mood disorders, anxiety disorder, and substance use disorder. Poisoning by substance was the most common self-harm method. The incidence of self-harm for patients with schizophrenia was 5.6 per 1,000 person-years, and the adjusted hazard ratio was 9.4 (95% confi dence interval = 8.3 - 10.7, p < 0.001). History of self-harm was the most signifi cant predictors of self-harm (adjusted HR = 18.56; 95% CI = 16.92 - 20.36, p < 0.001), followed by comorbid psychiatric disorders. Conclusion: Our study revealed that patients with schizophrenia had higher self-harm risk and more associated risk factors. We suggest that further public attention should be paid to self-harm prevention.
Key Word schizophrenia, self-harm, risk factors, incidence
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