Evaluating the Predictive Value of Frailty and Nutritional Indices for Postoperative Outcomes Following Thoracolumbar Fixation

Introduction: Risk indices, such as the 5-factor modified frailty index (mFI-5), Risk Analysis Index (RAI), and Geriatric Nutritional Risk Index (GNRI), have shown utility in predicting postoperative recovery from spinal surgery. The aim of this study is to assess the discriminatory accuracy of these indices in predicting postoperative complications following thoracolumbar fixation.

Methods: Thoracolumbar fixation cases from the ACS-NSQIP database (2015-2019) were analyzed for mortality, non-routine discharge (NRD), extended length of stay (eLOS), and complication rates, including Clavien-Dindo class IV complications (CDIV), stratified by RAI frailty tiers. AUC values for each outcome were used to compare the performance of models including mFI-5, RAI, GNRI, ASA, and a combined model incorporating RAI, GNRI, and ASA.

Results: In a cohort of 19,820 patients undergoing thoracolumbar fixation, frailty measured by the 5-factor modified frailty index (mFI-5), Risk Analysis Index (RAI), and Geriatric Nutritional Risk Index (GNRI) showed significant predictive value for mortality (mFI-5≥3: OR 6.451; RAI ≥ 41: OR 69.170; GNRI < 82: OR 21.829; p < 0.001), extended length of stay (eLOS) (severely frail: OR 2.658; RAI ≥ 41: OR 5.350; GNRI < 82: OR 8.566; p < 0.001), and non-home discharge (severely frail: OR 5.612; RAI ≥ 41: OR 14.731; GNRI < 82: OR 6.576; p < 0.001). All models also demonstrated significant predictive capacity for all complications, CD-IV, unplanned readmission, and reoperation. ROC analysis showed that the compound score provided the highest discriminative performance for mortality (C-statistic: 0.888; p < 0.001) and non-home discharge (C-statistic: 0.716; p < 0.001), as well as CD IV, readmission, and overall complications, outperforming the individual frailty indices.

Conclusion : The compound frailty model demonstrated superior predictive accuracy over individual models, emphasizing the utility of comprehensive frailty assessments in preoperative management for thoracolumbar fixation patients.