Superior discrimination of the Risk Analysis Index compared with the 5-item modified frailty index in 30-day outcome prediction after anterior cervical discectomy and fusion

OBJECTIVE The objective of this paper was to compare the predictive ability of the recalibrated Risk Analysis Index (RAI-rev) with the 5-item modified frailty index-5 (mFI-5) for postoperative outcomes of anterior cervical discectomy and METHODS This study was performed using data of adult (age > 18 years) ACDF patients obtained from the National Surgical Quality Improvement Program database during the years 2015-2019. Multivariate modeling and receiver operating characteristic (ROC) curve analysis, including area under the curve/C-statistic calculation with the DeLong test, were performed to evaluate the comparative discriminative ability of the RAI-rev and mFI-5 for 5 postoperative outcomes. RESULTS Both the RAI-rev and mFI-5 were independent predictors of increased postoperative mortality and morbidity in a cohort of 61,441 ACDF patients. In the ROC analysis for 30-day mortality prediction, C-statistics indicated a significantly better performance of the RAI-rev (C-statistic = 0.855, 95% CI 0.852-0.858) compared with the mFI-5 (C-statistic = 0.684, 95% CI 0.680-0.688) (p < 0.001, DeLong test). The results were similar for postoperative ACDF morbidity, Clavien-Dindo grade IV complications, nonhome discharge, and reoperation, demonstrating the superior discriminative ability of the RAI-rev compared with the mFI-5. CONCLUSIONS The RAI-rev demonstrates superior discrimination to the mFI-5 in predicting postoperative ACDF mortality and morbidity. To the authors' knowledge, this is the first study to document frailty as an independent risk factor for postoperative mortality after ACDF. The RAI-rev has conceptual fidelity to the frailty phenotype and may be more useful than the mFI-5 in preoperative ACDF risk stratification. Prospective validation of these findings is necessary, but patients with high RAI-rev scores may benefit from knowing that they might have an increased surgical risk for ACDF morbidity and mortality.