Being anaemic could more than triple the risk of dying within a year after having a stroke, according to research presented at the American Stroke Association’s International Stroke Conference 2012.
“Among stroke patients, severe anaemia is a potent predictor of dying throughout the first year after a stroke,” said Jason Sico, lead researcher and an assistant professor of neurology at Yale University School of Medicine in New Haven, USA.
Previous research has shown anaemic people who have a heart attack, heart failure or kidney disease are more likely to die within a year. Only a few small studies have focused on the link between stroke and anaemia-related death.
Researchers reviewed medical records of 3,750 men treated for a first ischaemic stroke at 131 Veterans Health Administration facilities in 2007.
Compared to stroke survivors who were not anaemic:
- Patients with severe anaemia were 3.5 times more likely to die while still in the hospital and 2.5 times more likely to die within a year.
- Stroke survivors with moderate anaemia were twice as likely to die within six to 12 months after a stroke.
- People with mild anaemia were about 1.5 times more likely to die within six to 12 months after a stroke.
In the study, a healthy hematocrit ranged from 38 to 42%; 33 to 37% was considered mild anaemia; 28 to 32% was moderate anaemia; and 27% or below indicated severe anaemia.
Researchers tracked whether stroke patients died in the hospital at 30 days, 60 days and at one year, based on how anaemic they were in the hospital.
To establish an independent association between anaemia and the risk of dying, researchers eliminated patient factors that could alter the results. These included age, stroke severity, stroke risk factors, vital signs, lab results and how healthy patients were before and after the stroke.
Based on the results, stroke patients with anaemia and their doctors should be aware of the increased risk of death and treat any modifiable causes for anaemia, Sico said.
Anaemia may be related to nutritional problems or blood loss in the stomach or intestines. Severe anemia may be treated with blood transfusions; however, studies have not been performed to see how safe and effective a blood transfusions are for someone hospitalised with an ischaemic stroke.
The research is ongoing and Sico hopes to determine within the next year which types of anaemia are associated with higher risks. Because this study looked only at men, future studies will need to determine the impact of anaemia on women after a stroke, particularly since anaemia may behave differently in women.
A possible explanation for the relationship between stroke and anaemia in men is that during an ischaemic stroke, anaemia disables the brain’s blood vessels from responding properly to the blood pressure change, Sico said. Another possibility, he said, is that people with anaemia often have other conditions associated with a higher stroke risk, such as heart disease and kidney disease.
Co-authors are Laura Myers, Dede Ordin, Linda Williams, and Dawn Bravata.