Modified 5-Item Frailty Index: A Useful Tool for Assessing the Impact of Frailty on Postoperative Morbidity and Mortality Following Surgical Fixation of Thoracolumbar Fractures

Objectives The modified 5-item frailty index (mFI-5) is a comorbidity-based risk stratification tool to predict adverse events following various neurological surgeries. This study aims to quantify the association between increased mFI-5 and postoperative complications and mortality following surgical fixation of traumatic thoracolumbar fractures. Methods The 2011-2021 American College of Surgeons - National Surgical Quality Improvement Program (ACS-NSQIP) dataset was used to identify patients undergoing fusion surgeries for thoracolumbar spine fractures. The mFI-5 score was calculated based on the presence of five major comorbidities: congestive heart failure within 30 days before surgery, insulin-dependent or noninsulin-dependent diabetes mellitus, chronic obstructive pulmonary disease, partially dependent or totally dependent functional health status at the time of surgery, and hypertension requiring medication. Multivariate analysis assessed the independent impact of increasing mFI-5 scores on postoperative 30-day morbidity and mortality while controlling for baseline clinical characteristics. Results A total of 66,904 patients were included in our analysis (54.2% female, mean age 62.27 ± 12.93 years). On univariate analysis, higher mFI-5 score was significantly associated with increased risks of superficial surgical site infection, deep surgical site infection, wound dehiscence, unplanned reoperation, pneumonia, unplanned intubation, postoperative ventilator use, progressive renal insufficiency, acute renal failure, urinary tract infection, stroke, myocardial infarction, cardiac arrest, pulmonary embolism, deep vein thrombosis, bleeding requiring transfusion, sepsis, septic shock, and longer hospital length of stay (LOS). On multivariate logistic regression, increasing mFI-5 score versus a mFI-5 score of zero was associated with higher odds of overall complications (mFI-5 ≥2: odds ratio [OR] 1.38 CI: 1.24 – 1.54, p<0.001; mFI-5 = 1: OR 1.18 CI: 1.11 – 1.24, p<0.001) and 30-day mortality (mFI-5 ≥2: OR 2.33 CI: 1.60 – 3.38, p<0.001). Conclusion This study demonstrates that frailty, when measured using the mFI-5, independently predicts postoperative complications, hospital LOS, and 30-day mortality after surgical repair of thoracolumbar fractures. These findings are important for risk stratification in patients undergoing thoracolumbar fusion surgery and for standardization in reporting outcomes after those procedures.