Outcomes after acute ischemic stroke in patients with thrombocytopenia or thrombocytosis

Thrombocytopenia may be associated with a greater risk of cerebral hemorrhage and thrombocytosis may be associated with a greater risk of cerebral thrombosis. There is a paucity of studies focused on the potential association between blood platelet count (BPC) and outcomes after acute ischemic stroke (AIS). We hypothesized that abnormal BPC is associated with poorer outcomes after AIS.

This study included data from the Ontario Stroke Registry on consecutive patients with AIS admitted between July 2003 and March 2008. Patients were divided into groups as follows: low BPC (<150,000/mm(3)), normal BPC (150,000 to 450,000/mm(3)) and high BPC (>450,000/mm(3)). Primary outcome measures were the frequency of moderate/severe strokes on admission (Canadian Neurologic Scale: <8), greater degree of disability at discharge (modified Rankin score: 3-6), and 30-day and 90-day mortality.

We included 9230 patients. Both low and high BPC were associated with higher 30-day mortality (p≤0.0335) and 90-day mortality (p≤0.048) following AIS. The Kaplan-Meier curves indicate that abnormal BPC is associated with greater mortality after AIS (p=0.0002). Nonetheless, abnormal BPC was not associated with initial stroke severity (p≥0.225), degree of disability (p≥0.3761), or length of stay in the acute stroke care center (p≥0.7818) after adjustment for major potential confounders.

Thrombocytopenia and thrombocytosis on the initial admission are associated with higher mortality after AIS. Abnormal BPC does not adversely affect the degree of initial impairment, disability at discharge, or length of stay in the acute care hospital after AIS.