Risk Analysis Index Outperforms the Modified Frailty Index in Predicting Outcomes in Thyroidectomy and Parathyroidectomy

Abstract Objective In an aging population, patients undergoing thyroidectomy and parathyroidectomy are at an increased risk of adverse outcomes; thus, measuring patient frailty is a key metric to assess risk. This study innovatively compares the utility of the Risk Analysis Index (RAI) with the 5‐factor Modified Frailty Index (mFI‐5) in predicting adverse postoperative outcomes. Study Design Retrospective cohort. Setting US hospitals. Methods Patients undergoing thyroidectomy or parathyroidectomy procedures were selected from the 2005 to 2020 NSQIP data set. RAI and mFI‐5 frailty scores were calculated and stratified: non‐frail (RAI: <21/mFI‐5: <1), pre‐frail (RAI: 21‐30/mFI‐5: 1), frail (RAI: 31‐40/mFI‐5: 2), and severely frail (RAI: 40+/mFI‐5: 3‐5) categories. Univariate and multivariate analyses were conducted, followed by receiver operating characteristic (ROC) curves, to evaluate the comparative discriminative thresholds of the indices. Results A cohort of 30,362 patients was identified with a median age of 56 years. Multivariate odds ratios showed that both indices were significant independent predictors of mortality (RAI: 15.508, P < .001; mFI‐5: 10.713, P < .001), extended length of stay (eLOS) (RAI: 9.480, P < .001; mFI‐5: 7.952, P < .001), non‐home discharge (RAI: 15.897, P < .001; mFI‐5: 9.346, P < .001), and Clavien‐Dindo (CD) II complications (RAI: 7.130, P < .001; mFI‐5: 3.760, P < .001). ROC analysis demonstrated significantly superior discrimination by the RAI for mortality (0.769 vs 0.650, P = .022), eLOS (0.712 vs 0.596, P < .001), non‐home discharge (0.763 vs 0.639, P < .001), CD II (0.739 vs 0.566, P < .001), CD IIIb (0.644 vs 0.587, P = .002), CD IV (0.707 vs 0.622, P < .001), and organ/space infection (0.719 vs 0.519, P < .001). Conclusion Both the RAI and mFI‐5 frailty indices are comparable, significant predictors of adverse events in thyroidectomy/parathyroidectomy. The RAI demonstrated superior discrimination for predicting postoperative morbidity across most outcomes, indicating it may be a superior clinical tool for identifying high‐risk patients. The RAI may better inform perioperative decision‐making, patient counseling, and resource allocation. Level of Evidence : 3.