Patients with anemia had an increased risk of death up to one year after suffering a stroke, according to a meta-analysis in the U.K.

Lead researcher Raphae S. Barlas, MA, of the Institute of Applied Health Sciences in Aberdeen, U.K., and colleagues published their results online in the Journal of the American Heart Association on Aug. 17.

The study included 8,013 patients with acute stroke who were admitted to Norfolk and Norwich University Hospital between January 2003 and May 2015. The mean age was 77.8 years old, while 52.4 percent of patients were women and 86.7 percent had ischemic stroke.

Of the patients, 24.5 percent had anemia when they were admitted to the hospital. The researchers said that low hemoglobin levels were associated with older age, increased stroke severity, higher prestroke disability and the increased comorbidity burden.

After adjusting for those and other factors, the researchers found that the presence of anemia was associated with increased odds of mortality up to a year after hospital admission. The association was less consistent for men with hemorrhagic stroke, according to the researchers.

They then conducted a systematic review and identified 10 studies that assessed the impact of anemia on stroke and 10 studies that evaluated the association between stroke and hemoglobin levels.

The researchers analyzed a total of 29,943 patients with stroke from the database study and the 20 studies from the systematic review. They found that anemia at hospital admission was associated with a 97 percent increased risk of mortality in ischemic stroke patients and a 46 percent increased risk of mortality in hemorrhagic stroke patients. In addition, elevated hemoglobin was associated with worse outcomes in acute stroke patients.

The study had a few potential limitations, according to the researchers, including the small number of patients with hemorrhagic stroke. They were also unable to control for unknown factors and unable to consider the duration of anemia or assess the impact of abnormal hemoglobin levels following a stroke. Thus, they mentioned that they could not determine if there was a causal relationship between anemia and excess mortality in stroke patients.

“We showed that a significant proportion of stroke patients have anemia at the time of stroke onset and that this is associated with increased mortality up to one year,” the researchers wrote. “The optimal treatment option in this patient group is unclear. Studies are required to examine the clinical and cost-effectiveness of interventions in this patient population in an acute stroke setting.”