Prospective Studies Are Required Prior to Revision of Perioperative Transfusion Guidelines

Goodnough et al¹ are to be commended for drawing attention to the impressive body of literature that documents the deleterious direct effects of anemia. Admittedly, anemia is ubiquitous and undertreated. However, the authors' statement that currently existing perisurgical transfusion guidelines "may misguide clinicians and underserve patients"¹ is not substantiated. Most studies they reference examined patients with progressive chronic medical conditions such as malignancy, congestive heart failure, and renal failure and are not applicable to surgical patients, a substantial percentage of whom are acutely ill. Of note, the study² they allude to that "suggests . . . mild anemia may be an independent risk factor for death following general surgery"¹ did not explicitly characterize patients by severity of illness, was observational in design, and does not address whether measures implemented to correct the anemia would impact any increased risk. The last point is of particular import, for while there is certainly a role for use of erythropoietin and intraoperative cell salvage techniques in surgical patients, currently, the primary means of treating anemia in the perioperative period is transfusion of allogenic packed red blood cells. This intervention is clearly appropriate in certain circumstances (ie, resuscitating overt hemorrhage or augmenting end-organ oxygen delivery when there is clinical evidence of ischemia), but there is an increasing realization that the risks of transfusion often outweigh its benefits. Transfusion carries a well-described inherent infectious risk,³ is associated with an increased rate of nosocomial infection,⁴ can precipitate hemolytic or nonhemolytic reactions, and may induce harmful immunomodulation.⁵ Transfusion-related acute lung injury, a potentially fatal condition, appears to occur most commonly in the perioperative period.⁶ In addition, there are data suggesting that anemia may be well tolerated in critically ill postoperative patients⁷ and in patients undergoing vascular surgery,⁸ elective coronary artery bypass graft surgery,^9- 10 and mitral valve surgery.¹¹ Given the current evidence, until additional prospective studies examine outcomes in surgical populations, any revision of perisurgical transfusion guidelines that would liberalize administration of allogenic packed red blood cells is premature.