Risk of suicide among patients with Parkinson disease

Importance: Parkinson disease (PD) is an increasingly common neurodegenerative disorder in many aging societies. Although comorbidities with mental disorders are common in PD, whether PD is associated with an increased risk of suicide is unclear. Objective: to use a large national representative PD cohort to compare the risk of suicide in patients with PD and control participants and identify potential risk factors. Design, setting, and participants: this nationwide population-based cohort study used linked data from Taiwan's National Health Insurance data set and Taiwan Death Registry between January 2002 and December 2016. Patients with incident PD diagnosed between January 2005 and December 2014 were followed up until December 2016. Four control participants from the general population were randomly selected by risk set sampling and were matched on age, sex, and residence to each affected individual. Data analysis occurred from June 2019 to October 2020. Exposures: diagnosis of PD retrieved from the National Health Insurance data set. Main outcomes and measures: suicide was recorded in the Taiwan Death Registry. Cox proportional models and hazard ratios (HRs) were used to estimate the association between PD and the risk of suicide over the follow-up period. Results: over 11 years, 35 891 patients with PD were followed up (17 482 women [48.7%]; mean [SD] age, 72.5 [10.1] years) and matched to 143 557 control participants (69 928 women [48.7%]; mean [SD] age, 72.5 [10.1] years). A total of 151 patients with PD (cumulative incidence, 66.6 per 100 000 [95% confidence limits [CL], 78.1-91.7]) and 300 control participants (cumulative incidence, 32.3 per 100 000 [95% CL, 36.2-40.5]) died by suicide. The risk of suicide was higher (HR, 2.1 [95% CL, 1.7-2.5]) in patients with PD than control participants, after adjustment for markers of socioeconomic position, medical comorbidities, and dementia. After controlling for mental disorders, the association between PD and suicide risk remained (HR, 1.9 [95% CL, 1.6-2.3]). Compared with control participants who died by suicide, those who died by suicide in the PD group were slightly younger (mean [SD] age: patients with PD, 74.0 [10.4] years vs control participants, 76.0 [10.2] years; P = .05) and more likely to be urban dwelling (medium urbanization, 39 patients with PD [25.8%] vs 115 control participants [38.3%]; high urbanization, 84 patients with PD [55.6%] vs 136 control participants [45.3%]; P = .03), have mental disorders (depression, 15 of 151 patients with PD [9.9%] vs 15 of 300 control participants [5.0%]; other mental disorders, 12 patients with PD [8.0%] vs 11 control participants [3.7%]; P = .02), and adopt jumping as a method of suicide (21 patients with PD [13.9%] vs 16 control participants [5.3%]; P < .01). Conclusions and relevance: in this population-based cohort study, Parkinson disease, a common neurodegenerative disorder common in elderly persons, was independently associated with an increased risk of suicide. Integrating mental health care into primary care and PD specialty care, along with socioenvironmental interventions, may help decrease the risk of suicide in patients with PD.