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

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.

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).

A total of 1733 acute ischemic stroke patients (149 underweight, BMI < 18.5 kg/m²; 1076 normal-weight, BMI = 18.5-24.9 kg/m²; 436 overweight, BMI = 25-29.9 kg/m²; and 72 obese, BMI > 30 kg/m²) 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/m² versus 23.7 kg/m², 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.

Anemia on admission was associated with stroke mortality independent of underweight status.