REVIEW OF THE CLINICAL-PRACTICE LITERATURE ON ALLOGENEIC RED-BLOOD-CELL TRANSFUSION

Objective: To review the evidence describing practice variation in the transfusion of allogeneic red blood cells as well as the risks, benef its, harms and costs associated with anemia and transfusion. Literatur e search and selection: Searches of MEDLINE from January 1966 to Decem ber 1996 were combined with manual searches of bibliographies and refe rences from experts. Two reviewers examined the abstracts of citations to identify those related to clinical practice involving red blood ce ll transfusions. Disagreement was resolved through consensus. Literatu re synthesis: Selected articles were classified by study design and to pic. Inferences were derived from the evidence. Results: Of the 189 ar ticles reviewed, 78 (41%) were interventional and 111 (59%) were obser vational studies. A number of observational studies reported a decreas e in the number of transfusions since the mid 1980s, significant pract ice variation among physicians, institutions and various medical and s urgical settings and rates of 4% to 66% of unnecessary transfusion. Of the 47 randomized clinical trials (RCTs) we found, 6 evaluated variou s ''transfusion thresholds. Only 1 of the 6 RCTs in patients with sick le-cell disease was considered level I evidence. There was no consensu s on a hemoglobin concentration that would act as a transfusion thresh old. Two cohort studies suggested that adverse outcomes from anemia ar e greatest in patients with cardiac disease. In 8 studies evaluating t he effect of hemoglobin concentration on health-related quality of lif e and symptoms such as dyspnea, fatigue and exercise capacity, no corr elations or associations were noted. Conclusion: The rate of transfusi on has decreased since 1985; practice varies significantly as does the rate of unnecessary transfusion. Education programs and the use of al gorithms may increase the appropriateness of RBC use. There was insuff icient evidence to justify setting an optimal hemoglobin concentration as a transfusion threshold following acute or chronic anemia. RCTs sh ould be conducted to determine best transfusion practice in a variety of clinical settings. Prospective cohort studies are also needed to de scribe transfusion practice.