Impact of Preoperative Anemia on Outcomes After Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis

Abstract

Objective: The aim of this study was to investigate the relationship of preoperative anemia and outcomes after posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS).

Methods: A retrospective cohort study was performed using the American College of Surgeons National Surgical Quality Improvement Program-Pediatric database from 2016 to 2018. All pediatric patients (age 10-18 years) with AIS undergoing PSF were identified. Two cohorts were categorized into anemic and nonanemic cohorts based on age-based and sex-based criteria for anemia. Thirty-day outcomes and readmission rates were evaluated.

Results: A total of 4929 patients were identified, of whom 592 (12.0%) were found to have preoperative anemia. The anemic cohort had a greater prevalence of comorbidities and longer operative times. Compared with the nonanemic cohort, the anemic cohort experienced significantly higher rates of perioperative bleed/transfusion (nonanemic, 67.4% vs. anemic, 73.5%; P = 0.004) and required a greater total amount of blood transfused (nonanemic, 283.2 ± 265.5 mL vs. anemic, 386.7 ± 342.6 mL; P < 0.001). The anemic cohort experienced significantly longer hospital stays (nonanemic, 3.8 ± 2.2 days vs. anemic, 4.2 ± 3.9 days; P = 0.001), yet discharge disposition (P = 0.58), 30-day complication rates (P = 0.79) and unplanned reoperation rates (P = 0.90) were similar between cohorts. On multivariate analysis, anemia was found to be an independent predictor of perioperative bleed/transfusion (odds ratio, 1.36; 95% confidence interval, 1.12-1.66; P = 0.002) as well as a longer length of hospital stay (relative risk, 0.46; 95% confidence interval, 0.25-0.67; P < 0.001) but was not an independent predictor for postoperative complications (P = 0.85).

Conclusions: Our study suggests that preoperative anemia may be a risk factor for a greater perioperative bleed/transfusion event and slightly longer length of stay; however, it was not associated with greater 30-day complication and readmission rates in patients with AIS undergoing PSF.

Keywords: Adolescent idiopathic scoliosis; Posterior spinal fusion; Preoperative anemia.