Efficacy of the five-item modified frailty index for predicting a poor prognosis in patients undergoing posterior lumbar interbody fusion surgery for lumbar spinal stenosis

Abstract

Objective: This study aimed to determine whether preoperative frailty assessed using the five-item modified frailty index (mFI-5) in patients undergoing posterior lumbar interbody fusion for lumbar spinal stenosis can predict poor patient outcomes.Methods: We retrospectively included 192 patients aged 18 years or older who were diagnosed with lumbar spinal stenosis and underwent posterior lumbar interbody fusion at a single hospital between March 2009 and February 2021. We calculated mFI-5 scores for these patients based on the following five comorbidities: (1) hypertension requiring medication, (2) diabetes mellitus, (3) history of chronic obstructive pulmonary disease or pneumonia, (4) history of congestive heart failure in the 30 days before surgery, and (5) partially or totally dependent functional health status at the time of surgery. The patients were categorized into three groups according to their mFI-5 scores, and these groups were analyzed. A P<0.05 was considered statistically significant in all analyses.Results: Length of hospital stay (LOS) was significantly associated with mFI-5 score (β=0.196, P=0.008), age (β=0.112, P=0.159), and surgical level (β=0.238, P<0.001). In patients with fusion at one or two levels, mFI-5 score showed the greatest association with LOS (β=0.188, P=0.016), followed by sex (β=0.137, P=0.065) and the number of fused segments (β=0.137, P=0.065).Conclusion: Frailty may not be an independent predictor, but it has significant predictive power for LOS in patients undergoing posterior lumbar interbody fusion for lumbar spinal stenosis, especially in patients undergoing fusion at one or two levels.