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Centre for Evidence-
Based Medicine

Transfusion: In critically ill patients may not decrease mortality

Clinical Bottom Line

In critically ill patients, the liberal use of blood transfusions (Hgb 10 g/dl) is not associated with a 5.5% or greater reduction in 30 day mortality.


A multicenter, randomized, controlled clinical of transfusion requirements in Critical Care
NEJM 1999;340:409-17

Clinical Question

In a critically ill patient, will restrictive blood transfusion practices be equivalent to liberal transfusion practices

Search Terms

"transfusion" and "critical care" and "death"

The Study

  • Concealed, unmasked, randomized, controlled clinical trial of equivalency with intention-to-treat analysis. Patients >16 years of age admitted to ICU with <9.0g/dL. Powered to detect a 5.5% or greater decease in 30 day motality.
  • Control Group (Liberal strategy of transfusion): (N=420, 416 analyzed); Transfuse to Hgb 10-12 g/dL
  • Experimental Group (Restrictive strategy of transfusion): (N=418, 413 analyzed); Transfuse to Hgb 7-9 g/dL.

The Evidence

Outcome Time CER EER RRR ARR [95% CI] NNT [95% CI]
Death 30 day 23% 19% 20% 4.6% [-0.8% - 10.2%] 22 [NNT 10 to infinity, NNH 35 to infinity]
60 day 26% 23% 14% 3.8% [-2.1% - 9.5%] 33 [NNT 11 to infinity, NNH 35 to infinity]


  1. Study terminated early because of decrease in enrollment to below 20% of predicted values
  2. Study powered to detect a 5.5 % decrease in mortality or greater so can not comment whether transfusion is associated with a smaller decrease in mortality. Since the outcome is mortality, any decrease in mortality may be clinically important
  3. Those patients who were not enrolled were slightly older, had similar APACHE scores and co-morbid diagnoses except for cardiac disease possibly limiting the generalizability of the results.
  4. Study had inadequate power to state whether these results apply to patients with significant coronary disease.
  5. Subgroup analysis suggests that restrictive transfusion may be associated with reduced 30 day mortality in patients less than 55 years of age (5.7% restrictive group and 13% in the liberal transfusion group) and in patients with APACHE II scores less than 20 (8.7% restrictive group and 16.1% liberal group).

CAT created by Martinez E, Pronovost PJ

Appraised By

Pronovost 1999

Expiry Date