Is Frailty the Missing Link? Assessing the Impact of the Modified 5-item Frailty Index on Outcomes in Metastatic Spine Tumor Surgery

Introduction: The modified 5-item frailty index (mFI-5) is a widely used tool to assess frailty and has been shown to predict postoperative complications in various surgical contexts. However, its utility in predicting outcomes in patients undergoing surgery for metastatic spine tumors is not well established. This study aims to evaluate the association between the mFI-5 score and postoperative complications and mortality in patients undergoing surgery for metastatic spine tumors.

Methods: A retrospective analysis was performed using the 2007-2021 ACS-NSQIP dataset to identify patients who underwent spine surgery for metastatic disease. The mFI-5 score was calculated based on the presence of five comorbidities: congestive heart failure, diabetes mellitus, chronic obstructive pulmonary disease, partially or totally dependent functional status, and hypertension requiring medication. Multivariate analysis was used to assess the independent impact of increasing mFI-5 scores on 30-day postoperative morbidity, mortality, and length of hospital stay (LOS), controlling for baseline clinical characteristics.

Results: A total of 3,120 patients were included in the analysis (58.9% male, mean age 62.3±12.7 years). On univariate analysis, a higher mFI-5 score was significantly associated with increased rates of organ space infection, pneumonia, failure to wean off ventilator>48 hours after surgery, urinary tract infection, cardiac arrest, myocardial infarction, and longer hospital LOS. Higher mFI-5 was associated with increased rate of 30-day morbidiy (mFI-5=0 41.5%, mFI-5=1 45%, mFI-5≥2 47.2%, OR 1.3 95% CI:1.1-1.5,p=0.02) and 30-day mortality (mFI-5=0 4.9%, mFI-5=1 6.6%, mFI-5≥2 10.7%, OR 2.3 95% CI:1.6-3.3,p < 0.001) after surgery. Multivariate logistic regression revealed that patients with an mFI-5 score ≥2 had significantly higher odds of overall complications (OR 1.3, 95% CI:1.1–1.5,p=0.04) and 30-day mortality (OR 2, 95% CI:1.4–2.9,p < 0.001) compared to those with an mFI-5 score of 0.

Conclusion : Frailty, as measured by the mFI-5 score, is an independent predictor of postoperative complications, longer hospital stays, and increased 30-day mortality following surgery for metastatic spine tumors. These findings emphasize the importance of incorporating frailty assessment into preoperative risk stratification for patients undergoing spine surgery for metastatic disease.