26 randomized control trials comparing the use of erythropoiesis stimulating agents (ESAs) with any other intervention in patients who underwent hip or knee surgeries were pooled to determine the effectiveness of ESAs in reducing the need for allogeneic blood transfusions, increasing hemoglobin level, and, also, to determine the frequency of thromboembolic events in elective orthopaedic surgeries that use ESAs. The results of the meta-analysis indicated that the use of preoperative ESAs reduces allogeneic blood transfusion in patients undergoing hip or knee surgery, and that hemoglobin levels following surgery are significantly higher in patients who received ESA than those who did not. No difference in the risk of developing thromboembolism between the two groups was discovered.