Modified Frailty Index as a Predictor of Postoperative Complications and Patient-Reported Outcomes after Posterior Cervical Decompression and Fusion

STUDY DESIGN: A retrospective cohort study. PURPOSE: To determine whether the 11-item modified frailty index (mFI) is associated with readmission rates, complication rates, revision rates, or differences in patient-reported outcome measures (PROMs) for patients undergoing posterior cervical decompression and fusion (PCDF). OVERVIEW OF LITERATURE: mFI incorporates preexisting medical comorbidities and dependency status to determine physiological reserve. Based on previous literature, it may be used as a predictive tool for identifying postoperative clinical and surgical outcomes. METHODS: Patients undergoing elective PCDF at our urban academic medical center from 2014 to 2020 were included. Patients were categorized by mFI scores (0-0.08, 0.09-0.17, 0.18-0.26, and ≥0.27). Univariate statistics compared demographics, comorbidities, and clinical/surgical outcomes. Multiple linear regression analysis evaluated the magnitude of improvement in PROMs at 1 year. RESULTS: A total of 165 patients were included and grouped by mFI scores: 0 (n=36), 0.09 (n=62), 0.18 (n=42), and ≥0.27 (n=30). The severe frailty group (mFI ≥0.27) was significantly more likely to be diabetic (p <0.001) and have a greater Elixhauser comorbidity index (p =0.001). They also had worse baseline Physical Component Score-12 (PCS-12) (p =0.011) and modified Japanese Orthopaedic Association (mJOA) (p =0.012) scores and worse 1-year postoperative PCS-12 (p =0.008) and mJOA (p =0.001) scores. On regression analysis, an mFI score of 0.18 was an independent predictor of greater improvement in ΔVisual Analog Scale neck (β =-2.26, p =0.022) and ΔVAS arm (β =-1.76, p =0.042). Regardless of frailty status, patients had similar 90-day readmission rates (p =0.752), complication rates (p =0.223), and revision rates (p =0.814), but patients with severe frailty were more likely to have longer hospital length of stay (p =0.006) and require non-home discharge (p <0.001). CONCLUSIONS: Similar improvements across most PROMs can be expected irrespective of the frailty status of patients undergoing PCDF. Complication rates, 90-day readmission rates, and revision rates are not significantly different when stratified by frailty status. However, patients with severe frailty are more likely to have longer hospital stays and require non-home discharge.