(I-688) Risk Analysis Index has Superior Discrimination compared to the Modified Frailty Index-5 in Outcome Prediction after Anterior Cervical Discectomy and Fusion

Introduction: Anterior cervical discectomy and fusion (ACDF) is one of the most commonly performed spine surgeries, with more than a million annual ACDF surgeries performed in the United States. The present study was performed to compare the predictive ability of the recalibrated Risk Analysis Index (RAI-rev) to the modified frailty index-5 (mFI-5) for postoperative outcomes of ACDF.

Methods: This study was performed on adult (age >18) ACDF patients’ data from the NSQIP database from 2015-2019. Multivariate modeling and receiver operating characteristic (ROC) curve analysis, including area under the curve (AUC)/C-statistics calculation with DeLong test, was performed to evaluate the comparative discriminative ability of RAI-rev and mFI-5 for five 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 significantly better performance of RAI-rev (C-statistic = 0.855, 95% CI 0.852-0.858) compared to 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, CDIV complications, NHD, and reoperation, demonstrating the superior discriminative ability of RAI-rev compared to mFI-5.

Conclusion : The RAI-rev demonstrates superior discrimination to the mFI-5 in predicting postoperative ACDF mortality and morbidity. This is the first study documenting 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 they might have increased surgical risk for ACDF morbidity and mortality.

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