Utility of GLFS-25 as a patient-reported outcome measure for older patients with lumbar spinal stenosis: A two-year retrospective cohort study

Background: The 25-question Geriatric Locomotive Function Scale (GLFS-25) is a patient-reported outcome measure (PROM) for assessing locomotive syndrome, which reflects mobility limitations due to musculoskeletal decline in older adults. Although lumbar spinal stenosis (LSS) is a major contributor to locomotive syndrome, the utility of GLFS-25 in evaluating the clinical status of older patients with LSS remains unclear. This study aimed to evaluate the GLFS-25 as a disease-specific PROM for older adults with LSS by comparing it with established tools such as the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and Zurich Claudication Questionnaire (ZCQ). Methods: This retrospective cohort study included 206 patients aged ≥65 years who underwent surgery for LSS. GLFS-25, JOABPEQ, and ZCQ scores were collected preoperatively and at 6 months, 1 year, and 2 years postoperatively. Correlations between the GLFS-25 and other PROMs were analyzed. Locomotive syndrome stages were determined based on GLFS-25 scores. The predictive accuracy of ZCQ satisfaction scores for postoperative improvement in the locomotive syndrome stage was assessed using receiver operating characteristic analysis. Results: GLFS-25 showed weak to moderate correlations with the five JOABPEQ domains and both ZCQ subscales. Patients with greater improvements in the locomotive syndrome stage also demonstrated higher proportions of treatment efficacy in the JOABPEQ domains. The ZCQ satisfaction score at 2 years postoperatively was a strong predictor of locomotive syndrome stage improvement, with an area under the curve of 0.858. The optimal satisfaction score cutoff for improvement in the locomotive syndrome stage was 1.917 (sensitivity: 80.0 %, specificity: 80.6 %). Conclusions: The GLFS-25 reflects clinical changes in older patients with LSS and correlates well with established PROMs. This tool may enable valid cross-sectional and longitudinal assessment of surgical outcomes for older patients with LSS. A ZCQ satisfaction score of approximately 1.9 indicates a meaningful improvement in the locomotive syndrome stage.