Incidence and method of suicide mortality in patients with schizophrenia: a Nationwide Cohort Study

Purpose: Suicide is a leading cause of death in patients with schizophrenia. This nationwide cohort study investigated the incidence of each suicide method in patients with schizophrenia compared with the general population. Methods: In total, records of 174,039 patients with schizophrenia were obtained from the National Health Insurance Research Database in Taiwan from 2001 to 2016. This schizophrenia cohort was linked with the national mortality database, and 26,926 patients died during this follow-up period. Of the deceased, 3033 had died by suicide. Univariate Cox regression was used to estimate the demographic variables associated with suicide. We estimated the difference in the proportion of each suicide method used in patients with schizophrenia compared with the general population. The incidence and standardized mortality ratio (SMR) of each suicide method were calculated and stratified based on sex. Results: Patients aged 25–34 years exhibited the highest suicide risk. Compared with the general population, patients with schizophrenia were more likely to commit suicide by jumping and drowning and less likely to use charcoal-burning and hanging. Women showed a higher incidence of suicide by drowning and jumping than did men. Comorbidity with substance use disorders (SUDs) was associated with a high suicide SMR (26.9, 95% confidence interval [CI] = 23.4–28.9), particularly for suicide by jumping (61.2, 95% CI = 48.3–76.3). Conclusions: Patients with schizophrenia had higher suicide rates for all methods than did the general population. Suicide method differed based on sex. Patients with SUDs exhibit a high SMR for each suicide method and warrant intensive clinical attention.