Abstract
Background: The 25-item Geriatric Locomotive Function Scale (GLFS-25) is often used to assess locomotive syndrome stage in older adults with lumbar spinal stenosis (LSS). However, locomotive syndrome stage three encompasses a wide score range, potentially masking clinically meaningful improvements. This study aimed to establish the minimal clinically important difference (MCID) for the GLFS-25 and determine whether MCID-based assessment better reflects surgical outcomes than stage-based evaluation.
Methods: This study included 314 patients aged 65 years and older with LSS who were preoperatively classified as having locomotive syndrome stage three. Patient-reported outcome measures, including the GLFS-25, the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), and Zurich Claudication Questionnaire (ZCQ), were administered before and at six months and 1 year after surgery. The MCID for the GLFS-25 was calculated using an anchor-based method, with the satisfaction item from the ZCQ at 1 year after surgery serving as the anchor. Patients were then categorized into four groups based on whether they achieved improvements in locomotive syndrome stage and/or the GLFS-25 MCID.
Results: A 19-point improvement in the GLFS-25 was determined to be the MCID, with an area under the receiver operating characteristic curve, sensitivity, and specificity of 0.80, 65.8%, and 90.2%, respectively. Based on postoperative changes, 129, 49, 33, and 103 patients achieved both stage and MCID improvement (group C), improvement in MCID alone (group M), improvement in stage alone (group S), and no improvement, respectively. Group C showed significantly better surgical effectiveness across all JOABPEQ domains. Group M showed significant improvements in four domains, whereas group S showed significant improvement in only one domain.
Conclusions: The newly established 19-point MCID for the GLFS-25 more accurately represented clinically meaningful improvement than stage-based evaluation. The combined use of MCID and stage classification may enhance outcome assessment after LSS surgery in older adults.
