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Table 6 Studies assessing the association between hemoglobin concentrations or anemia and subsequent clinical outcomes among patients with acute ischemic stroke

From: Anemia and red blood cell transfusion in neurocritical care

Study

Patients

Design and setting

Exposure

Outcome

Main result

Comment

Sacco and colleagues [174]

3481 ischemic stroke

Retrospective (prospective data-base)

Multi-center

Baseline hct (patients divided into quartiles)

Death at 28 days

Hct >46% associated with death, but only among women

Hct ≤40% represented lowest quartile; effects of more extreme anemia not reported

Diamond and colleagues [175]

1012 ischemic stroke

Retrospective

Single-center

Baseline hct

Median 41%; inter-quartile range 38 to 44%

Discharge home (rather than nursing facility)

High and low hct associated with worse outcome (U shaped curve)

Optimal hct 45%

Only 2% of patients had hct <30% at time of their stroke

Lowe and colleagues [177]

270 ischemic stroke

Retrospective

Single-center

Baseline hct

Death in hospital

Patients with high hct (≥50%) had higher mortality (66 to 71%)

Elderly (≥75) with hct <40% also had higher mortality (65%)

Allport and colleagues [178]

64 hemispheric ischemic stroke

Prospective

Single-center

Baseline hct

Median 42%; range 33 to 48%

Reperfusion, infarct growth on serial MRI

Higher hct associated with less reperfusion (OR = 0.53, P < 0.0001) and more infarct growth (OR = 1.26, P < 0.05)

This was a study of the effects of high hct; few patients were anemic

†Huang and colleagues [179]

774 ischemic stroke

Prospective

Single-center

Anemia (Hb <13 g/dl for men, <12 g/dl for women) (21%)

Death and mRS ≥3 at 3 years

Anemic patients more likely to die (OR = 2.2, P = 0.02) and to have a poor neurological outcome (67% vs. 60%, P = 0.07)

Numerous potential confounders not adjusted for; severity of anemia not well characterized

†Huang and colleagues [180]

66 ischemic stroke (complicating ICA occlusion)

Prospective

Single center

Anemia (Hb <13 for men, <12 for women)

Death or recurrent stroke at 2 years

Anemia associated with death or recurrent stroke at 2 years (OR = 5.1, P = 0.012)

Numerous potential confounders not adjusted for; severity of anemia not well characterized

Nybo and colleagues [181]

250 ischemic stroke

Retrospective

Single-center

Anemia (Hb <13 g/dl for men, <12 g/dl for women) (15%)

Death at 6 months

Anemia associated with greater risk of death (OR = 3.6, CI = 1.4 to 9.3)

Numerous potential confounders not adjusted for; severity of anemia not well characterized

Bhatia and colleagues [182]

116 ischemic or hemorrhagic stroke

Retrospective

Single-center

Baseline Hb

Death at 30 days

Hb not associated with risk of death

Degree of anemia relatively mild

Wade and colleagues [183]

1377 symptomatic cerebrovascular disease

Retrospective (post hoc review of prospective RCT)

Multi-center

Hb >15 g/dl vs. ≥15 g/dl at study entry

Stroke

Patients with Hb ≥15 had similar outcomes to patients with Hb <15 g/dl

This was a study of the effects of high Hb; few patients were anemic

LaRue and colleagues [184]

2077 ischemic or hemorrhagic stroke

Retrospective (prospective database)

Multi-center

Baseline hct (patients divided into quartiles)

Death in hospital

Hct not predictive of death (neither when high nor low)

Neurologic outcomes (other than death) not reported

  1. CI = confidence interval; Hb = hemoglobin; hct = hematocrit; ICA = internal carotid artery; MRI = magnetic resonance imaging; mRS = modified Rankin scale; OR = odds ratio; RCT = randomized controlled trial