Predictors of Red Blood Cell Transfusion in Bimaxillary Orthognathic Surgery: A Retrospective Study

Development and Validation of a Nomogram to Predict the Risk of Blood Transfusion in Orthognathic Patients

OBJECTIVE

This study aims to establish a nomogram to predict the probability of blood transfusion in patients with preoperative autologous blood donation before orthognathic surgery.

METHODS

The authors conducted a retrospective case-control study on consecutive orthognathic patients with preoperative autologous blood donation from January 2014 to December 2020. The outcome variable was the actual transfusion of autologous blood (ATAB). Predictors included patients' demographics, preoperative blood cell test, vital signs, American Society of Anesthesiologists classification, surgical procedure, operation duration, and blood loss. Univariable and multivariable logistic regressions were performed to identify independent risk factors associated with ATAB. A nomogram was constructed to predict the risk for ATAB. The performance of the nomogram was evaluated using the area under the receiver operating characteristic curve, calibration curve and the consistency index.

RESULTS

A total of 142 patients (75 males and 67 females) with an average age of 22.72 ± 5.34 years donated autologous blood before their orthognathic surgery. Patients in the transfusion group (n = 56) had significantly lower preoperative red blood cell counts (4.74 ± 0.55 × 109/L versus 4.98 ± 0.45 × 109/L, P = 0.0063), hemoglobin (141.48 ± 15.18 g/dL versus 150.33 ± 14.73 g/dL, P = 0.0008), and hematocrit (41.05% ± 4.03% versus 43.32% ± 3.42%, P = 0.0006), more bimaxillary osteotomies (92.86% versus 56.98%, P < 0.001), longer operation duration (348.4 ± 111.10 minutes versus 261.6 ± 115.44 minutes, P < 0.001), and more intraoperative blood loss (629.23 ± 273.06 ml versus 359.53 ± 222.84 ml, P < 0.001) than their counterparts (n = 86) in the non-transfusion group. Univariable and multivariable logistic regression demonstrated that only hemoglobin (adjusted odds ratio [OR] 0.864, 95% confidence interval [CI]:0.76-0.98, P = 0.026), operation procedures (adjusted OR 8.14, 95% CI:1.69-39.16, P = 0.009), and blood loss (adjusted OR 1.006, 95% CI:1.002-1.009, P < 0.001) were independent risk factors for ATAB. The area under the receiver operating characteristic curve of the nomogram was 0.823. The consistency index of the nomogram was 0.823. The calibration curve illustrated that the nomogram was highly consistent with the actual observation.

CONCLUSIONS

The nomogram is a simple and useful tool with good accuracy and performance in predicting the risk for blood transfusion.