The Utility of the 5 Factor Modified Frailty Index in Outcome Prediction for Patients with Chronic Subdural Hematoma Treated with Surgical Drainage

Abstract

Increasing frailty is a significant determinant of peri-operative morbidity and mortality within neurosurgical literature. This study investigates the predictive value of the mFI-5 for postoperative morbidity and mortality following surgical drainage of cSDH. A retrospective cohort study was performed on patients who underwent surgical evacuation of a cSDH. The mFI-5 score was calculated for each patient and used to stratify patients: pre-frail (mFI-5<2), frail (mFI-5=2), and severely frail (mFI-5>2). Multivariate Cox proportional hazards (CPH) regression analysis were used to identify factors associated with our primary outcomes: OS and 30-day readmission. Secondary outcomes included non-home discharge, length of stay, hematoma accumulation, development of new post-operative neurologic deficits, resolution of pre-operative neurologic deficits and a mRS>2 at discharge. 118 patients with a mean age of 74.4±11.9 were analyzed. All baseline demographics were similar across the three groups. On multivariate analysis, severely frail patients (N=24, 20.3%) had increased rates of 30-day readmission (HR 4.3, CPH regression p-value<0.001) and postoperative mortality (HR 3.1, CPH regression p-value<0.01) compared to the pre-frail cohort. Severely frail patients had increased rates of non-home disposition (HR 9.6, CPH regression p-value< 0.001), development of new post-operative neurologic deficits (HR 2.75, CPH regression p-value= 0.03), and hematoma reaccumulation (HR 4.07, CPH regression p-value= 0.004). A novel scoring system accounting for patient age and frailty was predictive of 90-day mortality (AUC 0.77). Frailty, measured by the mFI-5, and our novel scoring system hold a predictive value regarding outcomes for patients undergoing surgical drainage of a cSDH.