Change in Classification Grade by the SRS-Schwab Adult Spinal Deformity Classification Predicts Impact on Health-Related Quality of Life Measures Prospective Analysis of Operative and Nonoperative Treatment

Study Design. Multicenter, prospective, consecutive series. Objective. To evaluate responsiveness of the Scoliosis Research Society (SRS)-Schwab adult spinal deformity (ASD) classifi cation to changes in health-related quality of life (HRQOL) after treatment for ASD. Summary of Background Data. Ideally, a classifi cation system should describe and be responsive to changes in a disease state. We hypothesized that the SRS-Schwab classifi cation is responsive to changes in HRQOL measures after treatment for ASD. Methods. A multicenter, prospective, consecutive series from the International Spine Study Group. Inclusion criteria: ASD, age more than 18, operative or nonoperative treatment, baseline and 1-year radiographs, and HRQOL measures (Oswestry Disability Index [ODI], SRS-22, Short Form [SF]-36). The SRS-Schwab classifi cation includes a curve descriptor and 3 sagittal spinopelvic modifi ers (sagittal vertical axis [SVA], pelvic tilt, pelvic incidence/lumbar lordosis [PI-LL] mismatch). Changes in modifi ers at 1 year were assessed for impact on HRQOL from pretreatment values based on minimal clinically important differences. Results. Three hundred forty-one patients met criteria (mean age = 54; 85% females; 177 operative and 164 nonoperative). Change in pelvic tilt modifi er at 1-year follow-up was associated with changes in ODI and SRS-22 (total and appearance scores) (P = 0.034). Change in SVA modifi er at 1 year was associated with changes in ODI, SF-36 physical component score, and SRS-22 (total, activity, and appearance scores) (P = 0.037). Change in PI-LL modifi er at 1 year was associated with changes in SF-36 physical component score and SRS-22 (total, activity, and appearance scores) (P = 0.03). Patients with improvement of pelvic tilt, SVA, or PI-LL modifi ers were signifi cantly more likely to achieve minimal clinically important difference for ODI, SF-36 physical component score (SVA and PI-LL only), SRS activity, and SRS pain (PI-LL only). Conclusion. The SRS-Schwab classifi cation provides a validated system to evaluate ASD, and the classifi cation components correlate with HRQOL measures. This study demonstrates that the classifi cation modifi ers are responsive to changes in disease state and refl ect signifi cant changes in patient-reported outcomes.