Both Ends of Values in the Hemoglobin Spectrum Are Associated with Adverse Stroke Outcomes

Abstract

Background and purpose: Existing studies on the association between hemoglobin values and stroke outcomes mostly focus on the lower side and mortality, often the only and primary endpoint. The current study was conducted to assess the association between hemoglobin concentration and a variety of poor stroke outcomes in patients with acute ischemic stroke.

Methods: We studied 8,321 patients enrolled in the China National Stroke Registry (CNSR) between 2007 and 2008. Patients were divided into 7 groups, and a logistic regression model was used to evaluate the association. Endpoints of interest included 1-year all-cause mortality, stroke recurrence, combined endpoint, and stroke disability. Stroke disability was defined as a modified Rankin Scale of 2-6.

Results: Patients with low and high hemoglobin values (≤11.6 g/dL and >16.1 g/dL) had higher proportion of poststroke adverse events than those in other groups. As compared with the fourth group of hemoglobin values of 13.5-14.2 g/dL, the adjusted odds ratios (ORs) with 95% confidence interval (CI) of low hemoglobin values (≤11.6 g/dL) were 2.25 (1.72-2.93) for all-cause mortality, 1.30 (1.04-1.61) for stroke recurrence, 1.63 (1.33-2.01) for combined endpoint, and 1.37 (1.12-1.67) for stroke disability, respectively. And, the ORs of high hemoglobin values (>16.1 g/dL) for adverse stroke outcomes were 1.72 (1.25-2.37), 1.43 (1.13-1.82), 1.43 (1.13-1.81), and 1.31 (1.06-1.63), respectively. Stratified analysis showed significant interactions between sex and categories of hemoglobin values for all-cause mortality (p = 0.05), stroke recurrence (p = 0.03), and combined endpoint (p = 0.01) but not for stroke disability (p = 0.24).

Conclusions: Our study found both low and high hemoglobin values were associated with adverse stroke outcomes including all-cause mortality, stroke recurrence, combined endpoint, and stroke disability, which showed a U-shaped association. And, significant interactions between sex and hemoglobin concentration on all-cause mortality and stroke recurrence were also identified.

Keywords: Acute ischemic stroke; Disability; Hemoglobin value; Mortality; Stroke recurrence.