Association between new-onset Parkinson’s disease and suicide risk in South Korea: a nationwide cohort study

Abstract Background Parkinson’s disease (PD) is an increasingly common neurodegenerative disease in an aging society. Whether PD is associated with an increased suicide risk is unclear. Thus, we investigated the effect of new-onset PD on suicide. Methods Using the National Health Insurance Service Senior Sample Cohort of South Korea, 17,143 incident PD patients and 17,143 risk set controls, matched by propensity score, were selected for follow-up. The incidence rate of suicide and 95% confidence interval (CI) were calculated based on a generalized linear model of the Poisson distribution. Effect sizes were expressed as hazard ratios (HRs) using the Cox proportional hazards model with a robust variance estimator that incorporated clustering within matched pairs. Results The incidence rate of suicide was 206.7 cases per 100,000 person-years (95% CI, 172.8–246.9) among the PD cohort. Compared to the matched controls, patients with PD were 2.64 times (HR, 2.64; 95% CI, 1.31–5.30) more likely to commit suicide during the first 180 days of follow-up and 2.47 times (HR, 2.47; 95% CI, 1.42–4.28) within the first 365 days of follow-up. During the entire follow-up period, patients with PD were 2.26 times more likely to commit suicide than were their matched controls (HR, 2.26; 95% CI, 1.67–3.06). Conclusion Our findings indicated an increased risk of suicide in patients with new-onset PD, regardless of the period after diagnosis. Incorporating mental health care with social and environmental interventions into primary care and PD-specialized care can help reduce suicide risk in people with PD, improving suicide prevention, identification, and risk assessment.