A large nationwide retrospective cohort found that Parkinson disease was independently associated with a roughly 1.9-fold higher risk of a composite kidney outcome (ESKD, initiation of kidney replacement therapy, or ≥30% eGFR decline).

Clinically relevant for Parkinson's care and for trial/drug safety considerations (need for kidney monitoring and dose adjustments), but offers limited actionable mechanistic or targetable insight for Parkinson's therapeutic discovery.

BACKGROUND AND HYPOTHESIS: Parkinson disease is associated with systemic complications, but its impact on kidney function in the general population remains unclear. This study examined whether Parkinson disease is associated with an increased risk of kidney function decline in a large population-based cohort. METHODS: This retrospective cohort study used nationwide claims data that were linked to health checkup records (April 2014-August 2024). Individuals were classified according to the presence or absence of Parkinson disease at baseline using International Classification of Diseases, 10th Revision codes. The primary outcome was a composite kidney outcome, defined as incident end-stage kidney disease, initiation of kidney replacement therapy, or a ≥ 30% decline in estimated glomerular filtration rate. RESULTS: In the overall cohort of 1 659 421 individuals, the median age was 68 years (IQR, 61-72) and 41.9% were men; 11 497 (0.7%) had Parkinson disease. Over a median follow-up of 1 092 days (IQR, 631-1 520), 33 335 individuals reached the composite kidney outcome. Kaplan-Meier estimates showed a higher risk of the composite kidney outcome in individuals with Parkinson disease than in those without Parkinson disease (log-rank P < 0.001). In multivariable Cox models, Parkinson disease was independently associated with the composite kidney outcome (hazard ratio 1.91 [95% confidence interval 1.72-2.12]). CONCLUSIONS: In this nationwide cohort, Parkinson disease was independently associated with subsequent kidney function decline. These findings support closer monitoring of kidney function in adults with Parkinson disease.