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May 27, 1998

Perioperative Blood Transfusion—Reply

Author Affiliations

Margaret A.WinkerMD, Senior EditorIndividualAuthorPhil B.FontanarosaMD, Senior EditorIndividualAuthor

JAMA. 1998;279(20):1610. doi:10-1001/pubs.JAMA-ISSN-0098-7484-279-20-jbk0527

In Reply.—Dr Zuccalà and colleagues report the results of their study, which suggested that perioperative transfusion may be associated with an increased risk of mortality and postoperative fever. These results are different than the results of our study of transfusion in patients with hip fracture, which did not demonstrate a relationship between transfusion and postoperative mortality.

We believe several methodologic differences may explain the conflicting results. Our study included 8787 patients from 20 medical centers that had significant variability in transfusion rates. The study by Zuccalà et al included a much smaller number of patients (N=206) and restricted transfusion to patients with hemoglobin levels less than 95 g/L. As a result, there will be no variability in transfusion practice for patients with hemoglobin levels greater than 95 g/L. Therefore, it is advisable to exclude from the study those patients not eligible to receive a transfusion, as they contribute no information to the comparison of patients receiving transfusions vs those patients not receiving transfusions. Furthermore, to understand the clinical relevance of the analysis, the association between transfusion and outcome should be stratified by trigger hemoglobin level. The trigger hemoglobin level is the principal measure of the severity of disease for which transfusion might be administered and is likely to be related to both an increased risk of transfusion and mortality. For example, in Table 4 of our article, we display a stratified analysis of the effect of transfusion in patients with hemoglobin levels of 70 to 79, 80 to 99, and greater than 100 g/L.