Tim Walsh and colleagues successfully conducted a pilot study comparing a liberal transfusion threshold of 9 g/dL to restrictive transfusion threshold of 7 g/dL in 100 intensive care unit patients with hemoglobin levels less than 9 g/dL. All patients required mechanical ventilation for > 96 hours, were > 55 years of age, and were expected to need mechanical ventilation at least 24 hours post randomization.
The trial recruited well, created a meaningful difference in hemoglobin levels, and had relatively few protocol violations. At 30 days, there were 12 deaths (23.5%) in the restrictive group and 16 deaths (32.7%) in the liberal group; relative risk, 0.72 (0.38 to 1.36). At 180 days there was a trend favoring restrictive transfusion group (19 vs. 27 deaths); relative risk, 0.68 [95% CI, 0.44–1.05]. Given the small sample size, these results should be viewed as hypothesis generating. The limitations of the trial included that only 3% of ICU patients were enrolled and the difference in red blood cell transfusions was relatively small between the groups. This well conducted pilot demonstrates the feasibility of definitive trial.
Jeffrey L. Carson