Comparison of Suicide Risk by Mental Illness: a Retrospective Review of 14-Year Electronic Medical Records

Abstract

Background: Korea is one of the countries with the highest rate of suicide, while suicidality is known to be closely related to mental illnesses. The study aimed to evaluate the suicide rates in psychiatric patients, to compare it to that of the general population, and to investigate the differences among psychiatric diagnoses and comorbidities.

Methods: Medical records and mortality statistics of psychiatric patients at Seoul National University Hospital from 2003 to 2017 were reviewed. The standardized mortality ratio (SMR) for suicide was calculated to compare the psychiatric patients with the general population. The diagnosis-specific standardized mortality rate and hazard ratio (HR) were adjusted by age, sex, and psychiatric comorbidity (i.e., personality disorder and/or pain disorder).

Results: A total of 40,692 survivors or non-suicidal deaths and 597 suicidal death were included. The suicide rate among psychiatric patients was 5.13-fold higher than that of the general population. Psychotic disorder had the highest SMR (13.03; 95% confidence interval [CI], 11.23-15.03), followed by bipolar disorder (10.26; 95% CI, 7.97-13.00) and substance-related disorder (6.78; 95% CI, 4.14-10.47). In survival analysis, psychotic disorder had the highest HR (4.16; 95% CI, 2.86-6.05), which was further increased with younger age, male sex, and comorbidity of personality disorder.

Conclusion: All psychiatric patients are at a higher risk of suicide compared to the general population, and the risk is highest for those diagnosed with psychotic disorder.

Keywords: Epidemiology; Mental Disorders; Psychiatric Diagnosis; Suicide.

Fig. 1. Flowchart showing the process in which participants are divided into two groups. All psychiatric patients who visited Seoul National University Hospital outpatient, ward, or emergency room from 2003-03-01 to 2017-12-31 were totally 67,868. From them, those who visited less than 3 times were excluded. The National Statistical data was matched, and among the patients with death information, the patient with cause of death code X60–X84 or Y87.0 was classified as a suicidal deaths, otherwise a survivor of suicidal death. Finally, there were 40,692 survivors or non-suicidal deaths, and 597 suicidal death.

Fig. 2. Diagnosis-specific survivor curves for 14 years of follow-up. Fig. 2 is a survival analysis graph visualized the contents of Table 4. The diagnosis with the highest HR was psychotic disorder and psychotic disorder has the lowest survival rate. The next highest HR diagnosis was substance-related disorder and bipolar disorder. The diagnosis with the lowest risk of suicide was the group without a psychiatric diagnosis as the main diagnosis.

HR = hazard ratio.