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Program Number: B299
Session Name: Poster Session

Revised Risk Analysis Index Fails to Predict Postoperative Complications Better Than Previous Version and 5-Factor Modified Frailty Index in Soft Tissue Free Flap Tissue Transfer

Michael P Saturno; Rahul Guda; Olivia First; Christopher Connors; Raymond Chai, MD; Icahn School of Medicine at Mount Sinai

Introduction: Frailty assessments are a popular tool for measuring physiological reserve and predicting postoperative outcomes. Previously, the 5-factor modified Frailty Index (mFI-5) and the Risk Analysis Index-Administrative (RAI-A) were the most commonly used indices. However, a revised version of the RAI-A - the RAI-Revised (RAI-Rev) - was recently published in 2020 and its efficacy remains sparsely reported, especially as it applies to procedures requiring soft tissue free flap anastomosis. This study compares the relative capacity of the mFI-5, the RAI-A, and the RAI-Rev to predict the postoperative complications following free flap tissue transfer. 

Methods: The Current Procedural Terminology (CPT) codes were used to identify patients 18 years or older who underwent head and neck surgical intervention requiring free flap tissue transfer as reported by the National Surgical Quality Improvement Program (ACS-NSQIP) database between 2015–2020. Primary outcomes included mortality, unplanned readmission, reoperation, extended length of stay (ELOS), non-home discharge, Clavien-Dindo Class IV complications, and major complications. ELOS was defined as a hospital course duration within the upper quartile of the cohort. Univariate, multivariate, and receiver operating characteristic (ROC) curve analyses were conducted to compare the predictive ability of the RAI-Rev, RAI-A, and mFI-5 for 30-day postoperative outcomes. The ROC analyses generated area under the curve (AUC) values for each frailty index that were then statistically compared using the DeLong Test.

Results: Univariate analyses demonstrated that increasing frailty tiers were generally associated with an increased likelihood of postoperative complications across all three frailty indices when compared to their respective non-frail cohort (Table 1). Multivariate analyses revealed that increasing frailty tiers resulted in greater likelihood of an ELOS and major complication in all three frailty indices (Table 2). Increasing frailty tier within mFI-5 and RAI-Rev was associated with an increased risk of Clavien-Dindo Class IV complications, though there was no such correlation for RAI-A. None of the frailty scores reliably predicted increased risk of mortality, though the RAI-Rev qualitatively outperformed the other two indices in predicting this outcome on the ROC curve analysis (Figure 1). However, the RAI-Rev was not statistically superior in predicting any complication. Notably, the RAI-A displayed an AUC = 0.92 when predicting non-home discharge, which significantly outperformed both the mFI-5 (AUC = 0.57, DeLong Test p-value < .001) and RAI-Rev ( AUC = 0.61, DeLong Test p-value < .001) (Figure 2).

Conclusion: The mFI-5, RAI-A, and RAI-Rev variably predict postoperative complications in procedures requiring soft tissue free flap transfer. Comparing each index, the RAI-Rev offered a more favorable AUC when predicting mortality, though this difference was not statistically significant. However, the RAI-A outperformed both indices in predicting non-home discharge. These findings suggest that the three most common frailty assessments are largely comparable in categorizing patients into tiers that are positively associated with increased postoperative complication rates when compared to non-frail patients.  However, index tool selection is likely to be more effective when tailored to specific postoperative outcomes of interest.

 

 

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