Liberal or Restrictive Transfusion after Cardiac Surgery

To the Editor: In their article on red-cell transfusion, Murphy et al. (March 12 issue) 1 report substantial nonadherence to treatment in both study groups — one of which had a restrictive threshold for hemoglobin level in red-cell transfusions and one of which had a liberal threshold. Although nonadherence (defined as either the failure to transfuse red cells within 24 hours after a patient's hemoglobin fell below an assigned threshold or the administration of a transfusion when the hemoglobin level was above the assigned threshold) increases the likelihood of a null result for the primary outcome, it might confound the finding . . .