Predicting Complications Following Proximal Humerus Fracture Repair Using the 6-Item Modified Frailty Index.

Abstract

Frailty is a well-established predictor of poor outcomes after orthopaedic surgery. The 6-item Modified Frailty Index (mFI-6), which includes hypoalbuminemia, may provide enhanced risk stratification compared to the widely used 5-item Modified Frailty Index (mFI-5). The predictive value of the mFI-6 versus the mFI-5 for short-term complications after surgical management of proximal humerus fractures (PHFs) remains unclear. A retrospective analysis of the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database was conducted to identify patients who underwent open reduction and internal fixation, hemiarthroplasty, or total shoulder arthroplasty for PHFs from 2011 to 2023. Patients were stratified by mFI-6 score (< 3 vs. ≥ 3). Thirty-day outcomes, including readmission, mortality, complications, hospital length of stay, and discharge disposition, were measured. Receiver operating characteristic (ROC) analysis compared the predictive performance of the mFI-6 and mFI-5 for these outcomes. A total of 30,070 patients met inclusion criteria. 5.4% were classified as highly frail (mFI-6 ≥ 3). Patients with high mFI-6 scores had significantly increased rates of readmission (9.9% vs. 2.9%), mortality (1.6% vs. 0.2%), overall complications (15.2% vs. 4.7%), non-home discharge (29.1% vs 8.6%), and longer hospital stays (4 ± 5 days vs. 2 ± 4 days) (all P-values < 0.001). After multivariate regression, these outcomes remained independently associated with high mFI-6 scores. The area under the ROC curve for the mFI-6 was highest for mortality (AUC 0.751), showing consistently superior performance compared to the mFI-5 for readmission, mortality, complications, and non-home discharge. After stratifying by procedure, such differences remained across most outcomes. In patients undergoing operative management of PHFs, higher mFI-6 scores are strongly associated with adverse 30-day outcomes. The mFI-6 demonstrates improved predictive ability over the mFI-5, supporting its adoption for preoperative risk stratification in patients undergoing surgery for PHFs.