Determination of minimally clinically important differences for JOABPEQ measure after discectomy in patients with lumbar disc herniation.

Background: It is crucial to define if changes in patient-reported outcome (PRO) measure correspond to relevant clinical improvements. Aim of this study was to determine minimally clinically important differences (MCID) of the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) in patients with lumbar disc herniation (LDH) to assess surgical success.

Methods: A total of 127 patients with LDH consecutively referred to our clinic were enrolled into this prospective study between March 2012 and August 2015. All participants completed the JOABPEQ and the Oswestry Disability Index (ODI) score before surgery, and at 1 year after surgery. Surgical success was defined based on clinical consensus of the team and be used as anchor. The MCID value of the JOABPEQ subscales were estimated using two anchor-based methods: (I) average change procedure (responsiveness); and (II) receiver operating characteristic (ROC) curve analysis.

Results: The mean age of patients was 51.2±9.4 years, and there were 68 (53.5%) male. A total of 83.5% (106 cases) showed improvement based on the clinical consensus of the spine surgeon team at last follow-up. To assess surgical success, the two MCID calculation methods generated two optimal prediction thresholds on the JOABPEQ subscales (low back pain: 19.1, 22.4; lumbar function: 21.3, 24.2; walking ability: 24.5, 27.9; social life function: 14.3, 17.1; and mental health: 12.8, 14.8) for ROC analysis and average change procedure, respectively (P<0.002 for all of subscales in two methods). For all five subscales, the sensitivity and specificity were between 61.2 and 81.1 with AUC greater than 0.70.

Conclusions: These findings support the value of the MCID to assess surgical success for the JOABPEQ subscales in patients with LDH. This estimate may be a useful tool in clinical practice.