Ischemic Stroke Mortality Is More Strongly Associated with Anemia on Admission Than with Underweight Status

Background: Underweight patients have recently been reported as a group with a high risk of poststroke death. Anemia also increases mortality rates in stroke patients. However, the causal associations between body weight and anemia resulting in stroke-related death remain unclear. We examined the association of weight status and hemoglobin levels with 3-month mortality after ischemic stroke. Methods: The study enrolled all consecutive patients with acute ischemic stroke and no history of stroke admitted to our hospital between January 2010 and December 2013. The patients were categorized into 4 body mass index (BMI) categories (underweight, normal-weight, overweight, and obese). Anemia was evaluated according to the World Health Organization criteria (men, <13 g/dL; women, <12 g/dL). Results: A total of 1733 acute ischemic stroke patients (149 underweight, BMI < 18.5 kg/m(2); 1076 normal-weight, BMI = 18.5-24.9 kg/m(2); 436 overweight, BMI = 25-29.9 kg/m(2); and 72 obese, BMI > 30 kg/m(2)) were included. Death within 3 months occurred in 65 patients (underweight, 10.1%; normal-weight, 3.4%; overweight, 2.3%; and obese, 5.6%). Compared to nonanemic patients, those with anemia (n = 329, 19.0%) had lower BMI (21.8 kg/m(2) versus 23.7 kg/m(2), P < .001) and higher mortality rates (9.1% versus 2.5%, P < .001). Underweight status was associated with 3-month mortality after adjusting for age, sex, comorbidities, and initial stroke severity. However, in the models that included laboratory findings, it was anemia status (odds ratio, 2.81; 95% confidence interval, 1.46-5.43), not underweight status, that was independently associated with 3-month mortality. Conclusion: Anemia on admission was associated with stroke mortality independent of underweight status.