Risk factors for preoperative anemia in orthognathic surgery patients undergoing autologous blood donation: A cross-sectional study

In Japan, preoperative autologous blood donation (ABD) is widely performed in orthognathic surgery to avoid allogeneic transfusion. Although previous studies have examined postoperative hemoglobin (Hb) fluctuations and the safety of autologous blood donations, few have investigated Hb levels at hospital admission or the optimal timing between blood storage and admission. This study aimed to identify risk factors for preoperative anemia in patients undergoing orthognathic surgery with ABD. Seventy-five patients scheduled for sagittal split ramus osteotomy between January 2021 and December 2023 were retrospectively analyzed. Four hundred milliliters of autologous blood were collected from patients with Hb ≥ 11 g/dL. Anemia was defined as Hb < 13 g/dL at admission. Logistic regression was performed for sex; smoking status; body mass index; Hb levels at donation; and the timing of the interval from donation to admission. At admission, 41 patients (55%) presented with anemia. Independent risk factors for anemia were Hb < 14.2 g/dL at donation (odds ratio [OR]: 26.20, 95% confidence interval [CI]: 3.71-185.00, P < .05) and an interval ≤ 22 days between donation and admission (OR: 6.54, 95% CI: 1.11-38.70, P < .05). Sex had minimal impact. The 22-day threshold corresponded with the 2 to 3-week erythropoietic recovery period, whereas longer storage may have compromised blood quality due to storage lesions. Ensuring Hb ≥ 14.2 g/dL at donation and allowing ≥ 22 days between donation and admission may reduce the risk of preoperative anemia. These findings provide practical guidance for perioperative management in orthognathic surgery and may inform transfusion strategies in regions where ABD remains common.