Measuring Clinically Relevant Improvement After Lumbar Spine Surgery: Is It Time for Something New?

Abstract Background Context Minimum clinically important difference (MCID) for patient-reported outcome measures is commonly used to assess clinical improvement. However, recent literature suggests that an absolute point-change may not be an effective or reliable marker of response to treatment for patients with low or high baseline patient-reported outcome scores. The multitude of established MCIDs also makes it difficult to compare outcomes across studies and different spine surgery procedures. Purpose To determine whether a 30% reduction from baseline in disability and pain is a valid method for determining clinical improvement after lumbar spine surgery. Study Design Retrospective analysis of prospective data from a national spine registry, the Quality Outcomes Database (QOD). Patient Sample There were 23,280 participants undergoing elective lumbar spine surgery for degenerative disease who completed a baseline and follow-up assessment at 12 months. Outcome Measures Patient-reported disability (Oswestry Disability Index: ODI), back and leg pain (11-point Numeric Rating Scale: NRS), and satisfaction (NASS scale). Methods Patients completed baseline and a 12-month postoperative assessment to evaluate the outcomes of disability, pain, and satisfaction. The change in ODI and NRS pain scores was categorized as met (≥ 30%) or not met ( Results Thirty percent reduction in ODI and back and leg pain predicted satisfaction with more accuracy than absolute point-change values for the total population and across all procedure categories (p Conclusions A 30% reduction MCID either outperformed or was similar to absolute point-change MCID values. Results indicate that a 30% reduction (baseline to 12 months after surgery) in disability and pain is a valid method for determining clinically relevant improvement in a broad spine surgery population. Furthermore, a 30% reduction was most accurate for patients in the lowest and highest disability and lowest pain severity categories. A 30% reduction MCID allows for a standard cut-off for disability and pain that can be used to compare outcomes across various spine surgery procedures.