Impact of Hemoglobin Levels and Anemia on Mortality in Acute Stroke: Analysis of UK Regional Registry Data, Systematic Review, and Meta‐Analysis

Abstract

BackgroundThe impact of hemoglobin levels and anemia on stroke mortality remains controversial. We aimed to systematically assess this association and quantify the evidence.Methods and ResultsWe analyzed data from a cohort of 8013 stroke patients (mean±SD, 77.81±11.83 years) consecutively admitted over 11 years (January 2003 to May 2015) using a UK Regional Stroke Register. The impact of hemoglobin levels and anemia on mortality was assessed by sex‐specific values at different time points (7 and 14 days; 1, 3, and 6 months; 1 year) using multiple regression models controlling for confounders. Anemia was present in 24.5% of the cohort on admission and was associated with 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. Elevated hemoglobin was also associated with increased mortality, mainly within the first month. We then conducted a systematic review using the Embase and Medline databases. Twenty studies met the inclusion criteria. When combined with the cohort from the current study, the pooled population had 29 943 patients with stroke. The evidence base was quantified in a meta‐analysis. Anemia on admission was found to be associated with an increased risk of mortality in both ischemic stroke (8 studies; odds ratio 1.97 [95% CI 1.57–2.47]) and hemorrhagic stroke (4 studies; odds ratio 1.46 [95% CI 1.23–1.74]).ConclusionsStrong evidence suggests that patients with anemia have increased mortality with stroke. Targeted interventions in this patient population may improve outcomes and require further evaluation.

Anaemia at admission is associated with poor clinical outcome in cerebral venous thrombosis

“…The strength of the association between anaemia and poor clinical outcome in our CVT cohort is similar to results of studies on arterial ischaemic stroke and haemorrhagic stroke [6]. Our study may have been underpowered to detect an association with mortality.…”

“…Outcome (mRS[3][4][5][6] in specific subgroups in the presence of anaemia CI, confidence interval; mRS, modified Rankin Scale; OR, odds ratio. Binary logistic regression analysis based on the pooled estimate after multiple imputation to account for missing variables.…”

Is anemia associated with cognitive impairment and delirium among older acute surgical patients?

“…According to The Third National Health and Nutrition Examination Survey, the prevalence of World Health Organization‐defined anemia among community‐dwelling adults aged ≥65 years in the USA was 11.0% and 10.2% in men and women, respectively, rising to >20% in those >85 years . Contemporary literature in hospitalized patient populations mirrors these figures; in patients admitted with stroke (mean age ~78.0 years), anemia was present in ~25% of patients and indeed associated with high mortality …”

Risk factors for early cardiovascular mortality in patients with bipolar disorder

“…Comparisons with mentally healthy controls found that lower hemoglobin level could be an additional risk factor for circulatory mortality in BD. Strong evidence suggests that patients with anemia have increased mortality with cerebrovascular disease . The prevalence of anemia among chronic psychiatry patients is higher than the general population .…”

“…Strong evidence suggests that patients with anemia have increased mortality with cerebrovascular disease. 33 The prevalence of anemia among chronic psychiatry patients is higher than the general population. 34 Regular measures of hemoglobin of bipolar patients may be necessary to reliably detect associations between anemia and CVD mortality.…”