Sex differences and hemoglobin levels in relation to stroke outcomes

Abstract

Objective: Women have worse outcomes after stroke compared to men. Since women have lower hemoglobin values, we examined whether hemoglobin levels may associate with worse stroke outcomes in women.Methods: We retrospectively studied 274 patients enrolled in a prospective multicenter study.We explored the relationship of hemoglobin with clinical outcome at 6 months, as measured by the modified Rankin Scale (mRS). Ordinal logistic regression was used to evaluate the independent effect of hemoglobin on clinical outcome, and to explore the influence of sex on that association.Results: Women had a lower mean hemoglobin level (11.7 6 1.8 g/dL) compared to men (13.3 6 1.7 g/dL). Low hemoglobin was associated with worse 6-month mRS outcomes in univariate analysis (p , 0.001). Lower hemoglobin remained independently associated with poor outcome after adjustment for comorbid disease, stroke severity, age, and sex. The inclusion of hemoglobin in the model attenuated the independent effect of sex on outcome.Conclusions: Sex differences in stroke outcome are linked to lower hemoglobin level, which is more prevalent in women. Further examination of this potentially modifiable predictor is warranted. Neurology Women who have a stroke tend to recover less well than men, 1 resulting in greater dependency, institutionalization, 2-4 and poorer quality of life. 5 Several reasons for the disparity have been investigated, including sex differences in clinical presentation and resource use, 2,6 in acute stroke care, 2,7 and biological divergence related to sex steroid hormones. 1 Women with stroke are also older, which may account for some of the observed differences. 8,9 In the context of an expanding elderly population, it is expected that the proportion of women with stroke will further increase, 9 which amplifies the urgency of the problem.Women also have a lower hemoglobin level than men, and previous data have shown that hemoglobin level correlates with worse neuroimaging surrogate outcomes.10 This raises the possibility that a portion of the worse outcome may be mediated by hemoglobin level. The purpose of this study was to assess whether the difference in hemoglobin level between men and women was associated with neurologic outcome, and whether this might account for a proportion of the sex difference in stroke recovery previously observed.METHODS Study population. We retrospectively analyzed the clinical data collected at a single center, as part of a prospective multicenter study evaluating the utility of new CT-based neuroimaging technology to improve prediction of stroke subtype and outcome (Screening Technology and Outcome Project in Stroke [STOPStroke] Study). The STOPStroke Study enrolled consecutive patients who were evaluated by multimodal CT (noncontrast CT, CT angiography, CT perfusion) within 24 hours of symptom onset for symptoms consistent with an acute ischemic stroke. Clinical outcome status was determined using the modified Rankin Scale (mRS)

Hemoglobin Concentration and Risk of Incident Stroke in Community-Living Adults

“…Unfortunately, since more than 90% of women in this study fell in the post-menopausal age group, we did not have enough power to detect pre and post-menopausal differences in stroke risk. In addition, a prior study suggested that physiological differences in oxygen-carrying capacity may make women less tolerant of lower hemoglobin concentrations than men with respect to stroke recovery, 31 providing a possible explanation for why lower hemoglobin was associated with higher risk of stroke in the current study.…”

Low neurologic intensive care unit hemoglobin as a predictor for intra-arterial vasospasm therapy and poor discharge modified Rankin Scale in aneurysmal subarachnoid haemorrhage-induced cerebral vasospasm

“…Previously, mean hemoglobin levels during hospitalization for ischemic stroke have been associated with worse mRS at 6 months; using mean hemoglobin values as opposed to any single hemoglobin value probably provides a more comprehensive measure of blood oxygen carrying capacity throughout the post-ictal and cerebral vasospasm periods 6. Regarding the development of low mean NICU hemoglobin levels in our cohort, anemia in critically ill patients is thought to be multifactorial, stemming from intravenous fluid therapy, procedure-related hemorrhage, phlebotomy, nutritional deficiencies, renal disease, drug effects, impaired iron regulation, reduced erythrocyte lifespan, and reduced erythropoiesis 14…”

“…Additionally, caution should be used when contemplating red blood cell transfusions for symptomatic cerebral vasospasm as transfusion has been associated with significant morbidity including cerebral vasospasm, medical complications, infections, worse outcome, prothrombotic state, cognitive impairment, and mortality 8–10 13. Also, some reports suggest that increased blood viscosity associated with higher hemoglobin levels might impair CBF in the setting of acute ischemic stroke, thereby decreasing cerebral oxygenation; however, a recent analysis did not demonstrate any associations between increased blood viscosity and poor neurologic outcomes 6. Further investigations are necessary to determine the safety, efficacy, and optimal hemoglobin threshold for red blood cell transfusion (if any) in cerebral vasospasm 8.…”

Tracheostomy after Severe Ischemic Stroke: A Population-based Study

“…This was represented in the composite Elixhauser comorbidity score, in addition to individual variables of age, gender, race, coronary heart disease, congestive heart failure, deep vein thrombosis, renal insufficiency, chronic obstructive pulmonary disease, atrial fibrillation, pneumonia, and sepsis. [28–40] We also evaluated for potential confounders that could independently affect the likelihood of an invasive procedure being offered: hospital size (small, medium, or large), hospital type (teaching or nonteaching), median household income in the patient’s zip code, and primary insurance payer (Medicare, Medicaid, private insurance, or other).…”