Modified Frailty Index‐11—A New Predictor of Postoperative Complications in the Aging Thoracic Spinal Stenosis Patients

OBJECTIVE: Operation for thoracic spinal stenosis (TSS) is considered a high-risk surgery. Because of the frailty of elderly patients, the prediction for postoperative complications is crucial. This study investigated the relationship between frailty, as measured by the modified frailty index-11 (mFI-11), and postoperative complications in elderly patients with thoracic myelopathy secondary to TSS. METHODS: A retrospective review was conducted of 391 patients aged 65 years or older, with 209 males and 182 females, who underwent surgery for TSS at Peking University Third Hospital from 2012 to 2023. Patients were stratified into subgroups based on mFI-11 score. Data on perioperative complications, including systemic and local events, were collected. Univariate and multivariate analyses were performed to determine the association between frailty and perioperative complications and to identify independent risk factors. RESULTS: A total of 391 elderly patients undergoing decompression and fusion for TSS were included and categorized by mFI-11 score: 0 (n = 73), 0.09 (n = 159), 0.18 (n = 98), and ≥ 0.27 (n = 61). Multivariate analysis identified the mFI-11 as an independent risk factor for surgical site infection (SSI) (OR = 7.250, p = 0.022), gastrointestinal complications (OR = 2.461, p = 0.029), urologic complications (OR = 4.855, p = 0.001), respiratory complications (OR = 13.968, p = 0.033), postoperative fever (OR = 2.256, p < 0.001), and postoperative transfusion (OR = 1.962, p = 0.014). Moreover, mFI ≥ 0.27 is a threshold for severe complications (OR = 15.886, p = 0.017), and mFI ≥ 0.18 is a threshold for any postoperative complications (OR = 6.338, p < 0.001) and minor complications (OR = 5.915, p < 0.001). CONCLUSIONS: The mFI-11 score is an effective predictor of the risk of surgical site infection, gastrointestinal complications, urologic complications, respiratory complications, postoperative fever, and postoperative transfusion in elderly patients undergoing TSS surgery. Patients with mFI scores ≥ 0.18 are at a significantly higher risk of any postoperative complications or minor complications, with mFI scores ≥ 0.27 indicating severe complications. Frailty, as assessed by mFI-11, and non-neurological complications did not significantly impact the long-term recovery rate.