Suicide Risk and Associated Factors in Parkinson Disease: A Nationwide Cohort Study

Although increased mortality in patients with Parkinson disease (PD) is well documented, studies on suicide-related mortality have yielded conflicting results. Moreover, the impact of comorbidities, socioeconomic factors and health behaviours as potential risk factors for suicide remains underinvestigated. This study aimed to investigate suicide mortality risk in patients with PD and comprehensively elucidate the association between comorbidities, socioeconomic factors, health behaviours and suicide in PD.

This nationwide population-based cohort study used Korean National Health Insurance Service data from 2009, with a longitudinal follow-up until 31 December 2021. This study included 2,732,294 (PD, n = 4132; without PD, n = 2,728,162) individuals. PD was defined by ICD-10 code (G20) and registration code (V124). Comorbidities were identified using medical history, ICD-10 codes, laboratory data and prescribed medications. Health behaviours were obtained from a self-reported National Health Screening Program questionnaire. The primary outcome was suicide mortality, determined by ICD-10 codes for intentional self-harm (X60-X84).

Suicide mortality in patients with PD increased by 2.71-fold. Males with PD had more than a sevenfold higher risk (HR = 7.34, 95% CI, 5.25-10.26). Low-income patients with PD had an approximately fivefold higher risk compared to high-income non-PD individuals (HR = 5.10, 95% CI, 3.07-8.46). Patients with PD concomitant with depression (HR = 5.00, 95% CI, 3.06-8.16) and alcohol consumption (HR = 3.54, 95% CI, 2.14-5.89) also showed increased suicide risk.

This study suggests that patients with PD have a higher risk of suicide, particularly males, those with lower income, depression or alcohol consumption.