Risk of stroke in patients with idiopathic Parkinson disease

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.

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.

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.

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.