Risk of stroke in patients with idiopathic Parkinson disease

PURPOSE: Large population based studies on the association of Parkinson disease (PD) with stroke are scarce. This study aimed to quantify the risk of a first-time diagnosis of idiopathic PD in patients with a history of stroke, and to assess incidence rates for stroke in PD patients. METHODS: We used the UK-based General Practice Research Database to compare the prevalence of stroke/TIA in newly diagnosed PD patients and in a matched comparison group without PD between 1994 and 2005. We conducted a follow-up study with a nested case-control analysis to quantify the risk of incident stroke/TIA in relation to a previous PD diagnosis. RESULTS: A history of stroke/TIA was associated with a significantly increased relative risk of being diagnosed with PD compared to patients without such a history (adj. odds ratio [OR] 1.65, 95% confidence intervals [CI] 1.47-2.00). In the cohort study, the crude incidence rate ratios (IRRs) for incident hemorrhagic stroke, ischemic stroke or TIA were 0.66 (95% CI 0.26-1.72), 1.46 (95% CI 1.03-2.07) and 1.86 (95% CI 1.40-2.47), respectively. CONCLUSIONS: In this large observational study the risk of a PD diagnosis was significantly increased after a previous stroke event, as was the risk of a first-time ischemic stroke in newly diagnosed PD patients compared to persons free of PD.