Are Anemic Adults at Higher Risk of Fatal Stroke?

Individuals with anemia may be at greater risk of dying as a result of a stroke, according to a new study.

Noting that the impact of hemoglobin levels and anemia on stroke mortality remains controversial, a team including researchers from the University of Aberdeen in Scotland and Norwich Medical School in England aimed to systematically assess this association and quantify the evidence.

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To that end, the investigators analyzed data from a cohort of 8013 stroke patients consecutively admitted over an 11-year period from January 2003 to May 2015 using a UK Regional Stroke Register. The authors assessed the effect of hemoglobin levels and anemia on mortality by using sex-specific values at different points in time (7 and 14 days; 1, 3, and 6 months; and 1 year) using multiple regression models controlling for confounding variables.

Overall, anemia was present in 24.5% of the cohort at admission and was linked to increased odds of mortality at most of the time points examined up to 1 year following stroke. The association was less consistent for men with hemorrhagic stroke, according to the researchers, who added that elevated hemoglobin was also associated with increased mortality, primarily within the first month.

The team also conducted a systemic review using the Embase and MEDLINE databases, finding 20 studies that met the inclusion criteria. When combined with the cohort from the current study, the polled population included 29,943 patients with stroke. Anemia upon admission was found to be connected to a higher risk of mortality in both ischemic stroke and hemorrhagic stroke.

The current approach to managing anemia in primary and secondary care is "mainly determined by the cause of the anemia and whether it is symptomatic," said Phyo K. Myint, MD, a professor in the School of Medicine, Medical Sciences, and Nutrition at the University of Aberdeen, and a coauthor of the study.

With this research, he said, "We found a direct relationship between the level of anemia and outcome after stroke. This conveys 2 important messages for primary care physicians."

First, low-grade anemia "is not benign, even it is not associated with symptoms. Therefore, an attempt should be made to address the cause of anemia adequately," he said.  

Second, “because we now know from robust research evidence that anemia in stroke is associated with a worse outcome, identification of the people at such high risk, i.e., people with cardiovascular risk factors who are also anemic," continues Myint, "is a very important step in ensuring they do not have excess risk of mortality when and if stroke occurs."

—Mark McGraw

Reference:

Barlas RS, Honney K, Loke YK, et al. Impact of hemoglobin levels and anemia on mortality in acute stroke: analysis of UK Regional Registry Data, systematic review, and meta-analysis [published August 17, 2016]. J Am Heart Assoc. doi:10.1161/JAHA.115.003019.