Comparing Frailty Indices for Risk Stratification in Urologic Oncology: Which Index to Choose?

Objective: To compare the predictive ability of the modified Frailty Index (mFI) and the revised Risk Analysis Index (RAI-Rev) for perioperative outcomes in patients undergoing major urologic oncologic surgery, aiming to identify the optimal frailty screening tool for surgical risk stratification.

Methods: NSQIP was queried to identify patients undergoing radical prostatectomy, partial or radical nephrectomy, or radical cystectomy between 2013 and 2017. We investigated the association of mFI and RAI-Rev with the following 30-day perioperative outcomes using multivariable logistic regression: major complications, Clavien grade ≥4 complications, non-home discharge, 30-day readmission, and all-cause mortality. Receiver-operating characteristic curve analysis compared the predictive performances of the 2 frailty instruments, with differences between the C-statistics assessed using DeLong's test.

Results: Among 101,739 patients, 30-day major complication rates varied from 2.40% in prostatectomy to 26.86% in cystectomy, non-home discharge rates ranged from 1.92% to 13.54%, and mortality rates were between 0.16% and 1.43%. RAI-Rev showed higher discriminatory ability for mortality (C-statistic: 0.688-0.798) and non-home discharge (C-statistic: 0.638-0.734) compared to mFI (C-statistic: 0.594-0.677 and 0.593-0.639, respectively). Both frailty indices had similar discriminatory ability for major perioperative complications (C-statistic: 0.531-0.607). DeLong's test confirmed statistically significant differences in C-statistics between RAI-Rev and mFI for mortality (P <.001) and non-home discharge (P <.001) across all surgical cohorts.

Conclusion: RAI-Rev may have greater utility as a frailty prognostic tool than mFI among patients undergoing major urologic surgery. Prospective studies and clinical trials exploring frailty should consider these results during trial design.