Vascular disease and risk of fall-related injuries in Parkinson's disease: A nationwide cohort study in Sweden.

Introduction: Parkinson's disease (PD) patients are prone to fall and fall-related injuries (FI). Vascular disease is common in PD and is positively associated with falls in elderly. We aimed to evaluate the association of vascular disease with FI risk in PD.

Methods: A nationwide cohort study of patients with primary PD diagnosis in Sweden was performed using Swedish national registers. Patients with and without vascular disease were followed from PD diagnosis until subsequent FI or 2013-12-31. The association of vascular disease with FI risk was estimated as hazard ratio (HR) and 95 % confidence interval (CI) by Cox regression using attained age as underlying timescale.

Results: We identified 2734 and 6979 incident FI from 8025 PD patients with and 20,543 without vascular disease, respectively. Overall, vascular disease associated positively with subsequent FI, which was mainly driven by the significant risk elevation within the first 6 months following vascular disease (HR  [95 % CI] for PD diagnosed ≤75 years is 1.61 [1.39-1.87] and for PD diagnosed >75 years is 1.48 [1.32-1.65]). Thereafter, the association attenuated to null before it rebounded five years after exposure in PD diagnosed ≤75 years (HR  = 1.26, 95 % CI: 1.10-1.45); whereas for PD diagnosed >75 years, it dropped remarkably and remained non-significant 6 months after exposure. When vascular disease was restricted to stroke, we saw a similar temporal pattern except that the short-term HRs among younger patients were stronger, lasted longer, and declined continuously without rebound.

Conclusions: Fall prevention is crucial to PD patients immediately after a vascular event.