Asher, Anthony M.

BACKGROUND AND OBJECTIVES: Minimum clinically important differences (MCIDs) for patient-reported outcome metrics (PROMs) in patients with cervical spondylotic myelopathy (CSM) lack consensus on the most appropriate calculation method. This retrospective study aimed to identify the optimal MCIDs for commonly used PROMs in CSM. METHODS: The CSM database from the Quality Outcomes Database SpineCORe Study Group was analyzed. Baseline, 3-month, and 24-month PROM values for Neck Disability Index (NDI), 5-dimension Euro-quality of life (EQ-5D) in quality-adjusted life years, modified Japanese Orthopaedic Association (mJOA) score, and neck/arm pain numeric rating scale (NRS) were collected. MCIDs were calculated for each PROM using previously validated techniques. MCID values were compared using the area under the curve (AUC) with the North American Spine Society satisfaction scale as an anchor. RESULTS: A total of 1141 patients with CSM undergoing surgery were included in this analysis. Improvement of ≥30% from baseline was the optimal MCID for NDI and neck/arm NRS. At 24 months, the optimal percentage cutoff MCID for these instruments resulted in AUCs of 0.76, 0.72, and 0.67, similar to the 30% improvement method, with AUCs of 0.73, 0.71, and 0.67, respectively. Numeric cutoffs (0.065 at 3 months; 0.149 at 24 months) were the superior MCIDs for EQ-5D. For mJOA score, a severity-adjusted MCID outperformed other methods, yielding an AUC of 0.67 at 24 months. MCIDs were achieved in 63% of patients for NDI, 59% for neck pain NRS, 61% for arm pain NRS, 52% for EQ-5D, and 59% for mJOA score at 24 months. CONCLUSION: Using the Quality Outcomes Database SpineCORe data set, we defined optimal MCIDs for key PROMs in CSM. A ≥30% improvement from baseline was optimal in NDI and arm/neck NRS. An absolute numeric cutoff was superior for EQ-5D (0.149 at the 24-month follow-up). A severity-adjusted MCID performed best for mJOA score. These redefined benchmarks better capture the treatment impact and guide care decisions for patients with CSM.

Study Design. Retrospective analysis of prospectively collected registry data. Objective. The aim of this study was to compare the performance of 30% reduction to established absolute point-change values for measures of disability and pain in patients undergoing elective cervical spine surgery. Summary of Background Data. Recent studies recommend using a proportional change from baseline instead of an absolute point-change value to define minimum clinically important difference (MCID). Methods. Analyses included 13,179 patients who underwent cervical spine surgery for degenerative disease between April 2013 and February 2018. Participants completed a baseline and 12-month follow-up assessment that included questionnaires to assess disability (Neck Disability Index [NDI]), neck and arm pain (Numeric Rating Scale [NRS-NP/AP], and satisfaction [NASS scale]). Participants were classified as met or not met 30% reduction from baseline in each of the respective measures. The 30% reduction in scores at 12 months was compared to a wide range of established absolute point-change MCID values using receiver-operating characteristic curves, area under the receiver-operating characteristic curve (AUROC), and logistic regression analyses. These analyses were conducted for the entire patient cohort, as well as for subgroups based on baseline severity and surgical approach. Results. Thirty percent reduction in NDI and NRS-NP/AP scores predicted satisfaction with more accuracy than absolute point-change values for the total population and ACDF and posterior fusion procedures (P < 0.05). The largest AUROC differences, in favor of 30% reduction, were found for the lowest disability (ODI 0–20%: 16.8%) and bed-bound disability (ODI 81%–100%: 16.6%) categories. For pain, there was a 1.9% to 11% and 1.6% to 9.6% AUROC difference for no/mild neck and arm pain (NRS 0–4), respectively, in favor of a 30% reduction threshold. Conclusion. A 30% reduction from baseline is a valid method for determining MCID in disability and pain for patients undergoing cervical spine surgery. Level of Evidence: 3