The mortality rate of Parkinson's disease and related comorbidities: a nationwide population-based matched cohort study in Korea

Background:: previous studies on mortality of Parkinson's disease (PD) enrolled a relatively small number of participants and were conducted in western countries. The objective of this study was to evaluate mortality rate of PD using a large nationwide cohort in Korea and to evaluate effects comorbidities have on mortality in PD. Methods:: the nationwide population-based cohort study was conducted using the Korean National Health Insurance Service-National Sample Cohort data. Patients with a primary diagnosis of PD were selected from the database. A matched cohort without PD was enrolled through randomly matching patients by sex, age, year of diagnosis, residential area and income level to the PD group with a ratio of 1:9. The Cox proportional hazard model was used to assess mortality risk between the two cohorts. A logistic regression analysis was used to identify mortality risk factors in PD cohort. Results:: in total, 25,620 patients were enrolled. The Cox proportional regression model had an adjusted hazard ratio of 2.479 [95% confidence interval (CI), 2.272-2.704] for mortality in PD cohort. Comorbidities, such as ischaemic stroke [odds ratios (OR) = 2.314, 95% CI, 1.895-2.824], haemorrhagic stroke (OR = 2.281, 95% CI, 1.466-3.550) and chronic obstructive pulmonary disease (OR= 1.307, 95% CI, 1.048-1.630) were associated with increased mortality, whereas dyslipidemia (OR = 0.285, 95% CI, 0.227-0.358) was negatively correlated with mortality. Conclusion:: over the 10 year follow-up period, the PD cohort's mortality rate was 2.5 times higher than the comparison cohort. Understanding the effects that comorbidities have on morality in PD would be useful for predicting mortality in patients with PD.