Minimally clinically important differences for the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) following decompression surgery for lumbar spinal stenosis.

Decompression surgery is the standard treatment in lumbar spinal stenosis (LSS). Recent studies have shown that patient satisfaction following decompression surgery does not correspond well with outcomes measured by conventional patient-reported outcome measurements. Recent study reported that the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) is the most accurate outcome measurement to reflect patient satisfaction. Nevertheless, the JOABPEQ was not studied enough, especially along with the minimally clinically important differences (MCIDs), as JOABPEQ is relatively new questionnaire. The MCID is the minimum score change which patients perceive as beneficial. Thus, knowing the MCID is critical evaluating the efficacy of intervention. The aim of this study was to determine the MCIDs of the JOABPEQ for patients with LSS undergoing decompression surgery. Patients who underwent decompression surgery for LSS were consecutively enrolled if they had a complete set of questionnaires. We determined the MCIDs of each domain in the JOABPEQ using distribution-based and anchor-based methods. The MCIDs were determined to be 20.4 in low back pain, 15.6 in lumbar function, 16.8 in walking ability, 13.4 in social life function, and 9.4 in mental health by the distribution-based method. Using the anchor-based method, the MCIDs were determined to be 28.5, 16.5, 25.0, 21.5, and 14.5, respectively. The MCIDs of the JOABPEQ in LSS were slightly different from 20-point, which was proposed in the JOABPEQ user's manual. Our findings should be considered when evaluating LSS patients undergoing decompression surgery as JOABPEQ is not LSS specific.