Assessment of Frailty Indices and Charlson Comorbidity Index for Predicting Adverse Outcomes in Patients Undergoing Surgery for Spine Metastases: A National Database Analysis

OBJECTIVE: The aim of this study was to assess the predictive ability of Metastatic Spinal Tumor Frailty Index (MSTFI) and the Modified 5-Item Frailty Index (mFI-5) on adverse outcomes, compared with the known Charlson Comorbidity Index (CCI). METHODS: A retrospective cohort study was performed using National Surgical Quality Improvement Program database from 2011 to 2019. All adult patients undergoing various procedures for extradural spinal metastases were identified. Patients were stratified into frail and nonfrail cohorts based on CCI, mFI-5, and MSTFI scores. A multivariate logistic regression analysis was used to identify independent predictors of prolonged length of stay, nonroutine discharge, adverse events, and unplanned readmission. RESULTS: Of the 1613 patients included in this study, 21.4% had a CCI >0, 56.6% had an mFI-5 >0, and 76.7% of patients had an MSTFI >0. On multivariate analysis, all 3 indices were found to be predictive of nonroutine discharge (CCI: adjusted odds ratio [aOR], 1.41 vs. mFI-5: aOR, 1.37 vs. MSTFI: aOR, 1.5) and adverse events (CCI: aOR, 1.53 vs. mFl-5: aOR, 1.23 vs. MSTFI: aOR, 1.43). High CCI (adjusted relative risk, 1.67) and MSTFI (adjusted relative risk, 1.14), but not mFI-5, were also associated with a prolonged length of stay, whereas MSTFI was found to be the only significant predictor of unplanned readmission (aOR, 1.22). CONCLUSIONS: Our study suggests that MSTFI frailty index may be more sensitive than both CCI and mFI-5 in identifying adverse outcomes after spine surgery for metastases.