Acute ischemic stroke and abnormal blood hemoglobin concentration.

OBJECTIVES

This study examines whether low or high blood hemoglobin concentration (HGB) is associated with stroke severity, worse clinical outcomes, and poorer prognosis after acute ischemic stroke (AIS).

METHODS

This retrospective cohort study included data from the Ontario Stroke Registry on consecutive patients with AIS who were admitted between July 2003 and March 2008. We excluded patients taking anticonvulsants or iron supplement; patients with cancer, renal failure, history of gastro-intestinal or genitourinary bleeding, and pregnancy. Patients were divided into groups as follows: low HGB, normal HGB, and high HGB. Outcome measures included the frequency of greater degree of disability at discharge (modified Rankin score: 3-6), 7-day, 30-day and 90-day mortality, and length of stay in the acute stroke care hospital.

RESULTS

Hemoglobin levels higher than the upper limit of normal are associated with a greater disability at discharge (OR = 1.49, 95% CI: 1.03-2.15, P = 0.0331), and higher 30-day mortality (HR = 1.98, 95% CI: 1.44-2.74, P < 0.0001) after adjustment for major potential confounders. The Kaplan-Meier curves indicate that abnormal HGB levels are associated with higher mortality after AIS (P < 0.0001). HGB levels below the lower limit of normal are associated with longer lengths of stay in the acute care hospital (OR = 1.11, 95% CI: 1.02-1.22, P = 0.017). Elevated HGB was associated with greater neurological deficit on admission (OR = 1.45, 95% CI: 1.06-1.95, P = 0.0195).

CONCLUSIONS

Our results suggest that an elevated HGB on the initial admission is associated with more severe strokes, greater disability at discharge, and higher 30-day mortality after AIS. A low HGB on admission is associated with longer stay in the acute care hospital.