Table 6. Characteristics Determining Study Validity
StudyMethod of Stroke DiagnosisTime of Mortality MeasurementMethod of Mortality MeasurementConfounders Adjusted for in Multivariate Logistic RegressionHb Cutoffs UsedStroke Types Considered
Bhatia et al6Imaging30 daysTelephone, outpatient, or home interviewBoth considered together
Bussiere et al23Imaging30 days, 6 months, 1 yearPopulation registriesAge, sex, warfarin, INR, glucose, creatinine, blood pressure, IVHQuintiles, cutoffs; 100, 120, 140, 160 g/L; anemia defined as <120 g/LICH only
Chang et al24ImagingIn‐hospital mortalityAttending physicianAge, nadir Hb, ICH score, intubationAnemia (WHO definition)ICH only
Czlonkowska et al7Imaging or autopsy30 daysAge, decreased consciousness, severity of weaknessBoth considered together
Diedler et al25ImagingIn‐hospital mortalityAttending physicianAge, ICH volume, NIHSS, IVH, ICU stay, mechanical ventilation, RBC transfusion, mean HbAnemia definition: <12.1 g/L for women, <13.1 g/L for menICH only
Del Fabbro et al16In‐hospital, 1 yearTelephone interview, population registriesAge, GFR, comorbidities, functional statusAnemia (WHO definition)Both considered together
Gray et al26Clinical evaluation4 and 12 weeksAge, white cell count, hematocrit, Hb, urea>16 g/dL defined as elevatedBoth considered together
Hao et al2Imaging1 yearAge, sex, comorbidities, smoking, alcohol, NIHSS, eGFRAnemia (WHO definition)AIS only
Huang et al17Imaging3 yearsOutpatient interviewAge, comorbiditiesAnemia (WHO definition)AIS only
Kellert et al8Imaging3 monthsTelephone and outpatient interviewAge, NIHSS, blood glucose, microcytic and hypochromic RBCs, leukocytosis, creatinine, CRPAnemia (WHO definition)AIS only
Kumar et al18Imaging30 daysTelephone interview, medical records, population registryAge, sex, warfarin, ICH volume, IVH, glucose, WBCAnemia (WHO definition)ICH only
Kuramatsu et al19Imaging90 days and 1 yearTelephone interview, mailed questionnaireNIHSS, GCS, ICH score, ICH volume, IVH, Graeb score, midline shift, Hb, hematocrit, mechanical ventilation, pneumoniaAnemia (WHO definition)ICH only
Milionis et al20Imaging7 days, 3 months, 12 monthsMedical records, death certificate, population registryAge, sex, smoking, insurance, time to treatment, type of intervention, comorbidities, prior medication, BMI, blood pressure, heart rate, TOAST classification, metabolic parametersAnemia (WHO definition)AIS only
Nybo et al21Imaging6 monthsPopulation registryAge, sex, comorbidities, Scandinavian stroke scaleAnemia (WHO definition)AIS only
Park et al93 monthsTelephone interview, chart reviewAge, sex, blood pressure, prestroke mRS, NIHSS, comorbidities, blood glucose, thrombolysisPrespecified quintilesAIS only
Sharma et al27ImagingAge, BMI, comorbidities, Hb, eGFRHb <13 g/dLAIS only
Sico et al1ImagingIn‐hospitalAge, NIHSSHematocrit <31%AIS only
Tanne et al10ImagingMortality at 1 yearPopulation registryAge, sex, stroke type, NIHSS, prior disability, comorbiditiesAnemia (WHO definition)Both considered separately
Wade et al28ImagingCutoff at 15 g/dLAIS only
Zeng et al22ImagingDischarge, 30 days, 3, 6, 12 monthsTelephone interviewAge, sex, prestroke mRS, NIHSS, BMI, GCS, ICH volume, glucose, comorbidities, antithrombotic use, antihypoglycemic use, antihyperlipidemic use, family history, smoking, alcoholAnemia (WHO definition)ICH only
  • AIS indicates arterial ischemic stroke; BMI, body mass index; CRP, C‐reactive protein; eGFR, estimated glomerular filtration rate; GCS, Glasgow Coma Scale; GFR, glomerular filtration rate; Hb, hemoglobin; ICH, intracerebral hemorrhage; ICU, intensive care unit; INR, International Normalized Ratio; IVH, intraventricular hematoma; mRS, modified Rankin Scale score; NIHSS, National Institutes of Health Stroke Scale; RBC, red blood cell; WBC, white blood cell; WHO, World Health Organization.