Comparison of Serum Albumin and the Risk Analysis Index for Predicting Operation Delay in Adult Spinal Deformity Surgery

Introduction: Predictive metrics for adverse postoperative outcomes are increasingly studied in adult spinal deformity (ASD) surgery, which places a significant physiologic burden on older patients. This study sought to compare the predictive ability of the Risk Analysis Index (RAI) and serum albumin (SA) for operation delay in ASD patients.

Methods: The ACS-National Surgical Quality Improvement Program (NSQIP) database was queried for ASD surgery patients using diagnostic and procedural codes (2015-2020). RAI is a 9-factor, 14-item prospective assessment of frailty and functional status. SA is used as a surrogate for a patient's nutritional status. Primary outcomes included operation delay, defined as the top 95% of days from admission to operation, and mortality. Secondary outcomes included non-home discharge (NHD), extended length of stay (eLOS), and Clavien-Dindo Grade IV (CDIV) complications. The comparative discriminatory accuracy of SA and RAI for operation delay was determined using multivariate modeling and area under the receiver operating characteristic (AUROC) curve analysis.

Results: A total of 2,369 patients undergoing ASD surgery were identified (58.3% female, median age=64 years, IQR:54-71). Adverse postoperative outcomes included NHD (38.4%, N=920), eLOS (24.7%, N=593), CDIV complications (8.5%, N=204), and mortality (1.0%, N=24). Operation delay (>3days) was recorded in 141 (5.9%) patients. SA demonstrated robust discriminatory accuracy for prediction of operation delay in AUROC curve analysis (C-statistic: 0.81, 95%CI:0.77−0.86, p< 0.001) compared to RAI (C-statistic: 0.59, 95% CI:0.55−0.63, p< 0.001)(DeLong test, p< 0.01). In multivariable logistic regression, adjusted for potential confounders including patient SA, RAI, and comorbidities, patients who experienced operation delay had increased risk for mortality (OR: 3.38, 95% CI:1.08-10.63, p=0.037), NHD (OR=2.15, 95% CI:1.42-3.27, p< 0.001), eLOS (OR=2.38, 95%CI:1.60-3.55, p< 0.001), and CDIV complications (OR=2.32, 95%CI:1.40-3.87, p= 0.001).

Conclusion : Serum albumin demonstrates superior discriminatory accuracy than RAI for predicting operation delay in ASD surgery, which is associated with greatest increased risk for mortality and eLOS. Hospitalized ASD patients may undergo preoperative risk stratification using serum albumin to inform perioperative management and promote timely surgical intervention.