Risk of All-Cause and Suicide Death in Patients With Schizophrenia: An Entire-Population Longitudinal Study in Taiwan

Schizophrenia increases mortality from all causes and specific causes. Comprehensive research on modifiable risk factors for early mortality from multiple sources is needed.

Taiwan's National Health Insurance Research Database, which contains claims data from a lifetime insurance program for the whole population, provided extensive medical inpatient and outpatient data categorized by ICD-9-CM and ICD-10 for this nationwide retrospective longitudinal cohort study. The National Mortality Registry provided data on all-cause, natural, suicide, and accidental deaths. 191,553 patients with schizophrenia and 26,362,448 individuals without schizophrenia were monitored from January 1, 2003, to December 31, 2017. Adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for mortality risk were calculated using Cox regression models. We compared different mortality risks associated with schizophrenia across age, sex, and Charlson Comorbidity Index (CCI) subgroups.

We found that schizophrenia results in a relatively higher increase in suicidal mortality in those aged ≤ 20 years (aHR = 15.55; 95% CI, 13.95-17.34), and that effect decreased with age. The effect of schizophrenia in female individuals (suicide death: female, aHR = 11.82, 95% CI, 11.21-12.46; male, aHR = 8.11, 95% CI, 7.77-8.47; difference, P < .001) and individuals without comorbidity (natural cause of death, CCI = 0 aHR = 5.94, 95% CI, 5.68-6.22; CCI = 1-2 aHR = 3.62, 95% CI, 3.52-3.73; CCI > 2 aHR = 1.61, 95% CI, 1.58-1.64) led to comparatively higher mortality risks. The effect of schizophrenia in individuals with AIDS (suicide death, aHR = 2.73, 95% CI, 1.70-4.39) resulted in a relatively smaller increase in suicide mortality compared to individuals with other comorbidities; however, in patients with connective tissue diseases, a diagnosis of schizophrenia still leads to an alarming increase in natural and unnatural mortality.

Schizophrenia in combination with younger age, female sex, comorbid connective tissue disease, or major organ problems necessitates more tailored countermeasures to lessen the higher mortality risk in these patients compared with patients who have these characteristics and conditions but do not have schizophrenia.