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Table 4 Clinical studies assessing the association between hemoglobin concentrations, anemia, or transfusion and subsequent outcomes among patients with traumatic brain injury

From: Anemia and red blood cell transfusion in neurocritical care

Study

Patients

Design and setting

Exposure

Pre-transfusion Hb or Hct

Analysis (variables)

Main result

Carlson and colleagues [143]

169

Retrospective

Single-center

- Number of days hct <30%

- Nadir hct

- RBC transfusion

Not reported

Linear regression assessing GOS as continuous variable

- Number of RBC units, lowest hct associated with worse discharge outcome

- Number of days hct <30% associated with better outcome

‡Steyerberg and colleagues [144]

3554

Post hoc analysis of several RCTs

Multi-center

Admission Hb (median 12.7 g/dl)

Not relevant

Logistic regression (10 covariates)

- Lower Hb associated with poor 3 to 6 month outcome (OR for 14.3 g/dl vs. 10.8 g/dl = 0.78, 0.70 to 0.87)

- Laboratory variables (Hb and glucose) improved prognostic models

Duane and colleagues [145]

788

Retrospective

Single-center

Hb in first 72 hours

RBC transfusion

Not reported

Logistic regression (age, ISS, total blood products)

- Minimum hemoglobin in first 72 hours associated with hospital mortality (OR = 0.86, 0.73 to 1.0 per g/dl increment)

- RBC transfusions not associated with mortality, but with nosocomial infection

Salim and colleagues [146]

1150

Retrospective (prospective database)

Single-center

Anemia (Hb <9 g/dl; occurred in 46%) and RBC transfusion (46%)

Not reported

Logistic regression (10 covariates)

- RBC transfusion associated with hospital mortality (OR = 2.2, P = 0.004) and complications (OR = 3.7, P < 0.0001)

- Anemia associated with adverse outcomes only when transfusion not included in model

George and colleagues [147]

82 (Hb 8.0 to 10.0 g/dl)

Retrospective

Single-center

RBC transfusion (52%)

8.6 g/dl

Cox proportional hazard regression (age, motor GCS, blood ethanol, lowest Na+, complications)

RBC transfusion predicted mortality (P < 0.05)

‡Van Beek and colleagues [148]

3872

Post hoc analysis of several RCTs

Multi-center

Admission Hb

Not relevant

Logistic regression (age, motor score, pupil reactivity)

- Lower Hb associated with higher risk of death/vegetative state at 3 to 6 months (OR = 0.69, 0.60 to 0.81, for 75th percentile vs. 25th percentile)

Schirmer-Makalsen and colleagues [149]

133

Retrospective

Single-center

Hb ever <8 g/dl (22%)

Not reported

Logistic regression (10 covariates)

A single Hb <8 g/dl did not predict adverse outcome

McIntyre and colleagues [150]

67

Post hoc analysis of RCT

Multi-center

Comparison of transfusion thresholds of 7.0 g/dl vs. 10.0 g/dl

Not reported

Logistic regression (age, APACHE II, PAC use)

- 30-day mortality 17% in restrictive group vs. 13% in liberal group (P = 0.64)

- Development of MOD and ICU LOS similar in both groups

Robertson and colleagues [151]

102

Prospective

Single-center

Hb at time of CBF determination

Not reported

Logistic regression (age, CBF, GCS, CPP, CMRO2)

- Lower Hb associated with unfavorable GOS after 3 months

  1. ‡ Based, in part, on same datasets
  2. APACHE = Acute Physiology and Chronic Health Evaluation; CBF = cerebral blood flow; CMRO2 = cerebral metabolic rate; CPP = cerebral perfusion pressure; GCS = Glasgow Coma Scale; GOS = Glasgow Outcome Scale; Hb = hemoglobin; hct = hematocrit; ICU = intensive care unit; ISS = injury severity score; LOS = length of stay; MOD = multiple organ dysfunction; OR = odds ratio; PAC = pulmonary artery catheter; RBC = red blood cell; RCT = randomized controlled trial.