Worse Preoperative Disability is Predictive of Improvement in Disability After Complex Adult Spinal Deformity Surgery

Study Design: Retrospective Cohort Study. Objectives: Few previous studies have examined the relationship between preoperative disability and patient outcomes after complex adult spinal deformity surgery. In this study, we hypothesized that patients with worse preoperative disability would be more likely achieve a clinically significant improvement in their symptoms after surgery. Methods: Demographics, comorbidities, surgical data, and health related survey results were analyzed from a consecutive series of adults (>= 18 years old) who underwent spinal deformity correction, instrumentation, and fusion. Patients included had 6 or more levels fused and their surgery performed at single institution between 2015 and 2018 with minimum 2 year follow up. Results: A total of 108 patients met inclusion criteria. Bivariate analysis demonstrated the following as having a greater probability of reaching minimum clinically important difference (MCID) at 2 years postoperatively: >50 th percentile Oswestry Disability Index (ODI) score (ODI >36), cardiac comorbidities, and use of pelvic fixation, pedicle subtraction osteotomy, and transforaminal lumbar interbody fusion. Conversely, baseline Scoliosis research society score (SRS) >50th percentile (SRS >= 62) and use of vertebral column resection (VCR) were significant predictors of not reaching MCID at 2 years. On logistic regression analysis, >50 th percentile ODI score (ODI >36) was identified as the only independent predictor of achieving MCID. Conclusions: Patients with greater disability, independent of other preoperative or surgical factors, are more likely to have clinically significant improvement in their daily functioning after complex deformity surgery. For patients who undergo surgical intervention for severe or progressive deformity, including VCR, MCID might be an ineffective outcome measure.