Prediction of massive blood loss in scoliosis surgery from preoperative variables.

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To identify predictors of massive blood loss after scoliosis surgery.

SUMMARY OF BACKGROUND DATA

Scoliosis surgery may be associated with considerable blood loss. Many blood conservation techniques have been used to reduce the allogeneic transfusion. An ability to identify patients with high risk of massive blood loss preoperatively may be helpful for appropriate use of these techniques.

METHODS

Data of patients undergoing scoliosis surgery between June 1, 2011, and October 31, 2011, were collected. Preoperative information and total blood loss, which was calculated as the sum of intraoperative and postoperative estimated blood loss, were recorded. Patients were divided into 2 groups, retrospectively: group A (n = 95) with the total blood loss more than 30% of estimated blood volume and group B (n = 64) with the total blood loss of 30% of estimated blood volume or less. Preoperative data were compared between the groups. Significant variables were selected for a forward stepwise binary logistic regression analysis to determine the independent risk factors of massive blood loss.

RESULTS

More than half of the patients (59.7%) undergoing scoliosis surgery had massive blood loss. Patients in group A were shorter (P = 0.01) and had larger preoperative Cobb angle (P < 0.01), more levels fused (P < 0.01), and more osteotomies (P < 0.01) than those in group B. Preoperative Cobb angle more than 50º (P = 0.017, odds ratio = 2.47, 95% confidence interval: 1.17-5.20), the number of fused levels more than 6 (P = 0.014, odds ratio = 3.70, 95% confidence interval: 1.31-10.49), and osteotomy (P = 0.000, odds ratio = 4.64, 95% confidence interval: 1.97-10.94) were determined to be the independent risk factors of massive blood loss in scoliosis surgery.

CONCLUSION

Risk of massive blood loss (total blood loss > 30% of estimated blood volume) in patients with scoliosis could increase, if they (1) had preoperative Cobb angle larger than 50º or (2) planned to undergo osteotomy or fusion of more than 6 levels.