Systemic lupus erythematosus is associated with increased risk of Parkinson’s disease

A small number of studies have suggested an association between systemic lupus erythematosus (SLE) and Parkinson’s disease (PD). This study aimed to determine the risk of incident PD among Korean patients with SLE. A nationwide retrospective cohort study using the claims database of the National Health Insurance Service of Korea was conducted. Patients above 40 years of age diagnosed with SLE between 2010 and 2015 were included in the study. The primary outcome of the study was incident PD, defined by registration in the rare intractable diseases program for PD and an ICD-10 code of G20. Subjects were followed until PD diagnosis or the end of 2017. We estimated the cumulative incidence of PD among the SLE cohort and compared this to that in a 1:5 age- and sex-matched control group. Totals of 11,615 SLE cases and 58,075 matched controls were identified. The cumulative incidence rate of PD was 0.7 per 1000 person-years in the SLE cohort. The crude hazard ratio (HR) of incident PD was 1.71 (95% CI: 1.25–2.36) among the SLE cohort compared to the control group. The HR was 1.59 (95% CI: 1.15–2.20) after adjustment for age, sex, income, and baseline comorbidities. This study demonstrated that patients with SLE had an increased risk of incident PD compared to non-SLE controls. Further research is required to determine the mechanism underlying this and to elucidate the precise role of systemic inflammation in the development of PD in patients with SLE.