Can Baseline Disability Predict Outcomes in Adult Spinal Deformity Surgery?

Abstract

Study Design. Retrospective Cohort Study Objective. To assess if there is a threshold of baseline disability, beyond which the patient reported outcomes after surgical correction of ASD are adversely impacted?. Background. Patient reported outcomes vary after correction of adult spinal deformity, even when patients are optimally realigned. There is a paucity of literature examining the impact of baseline disability on patient reported outcomes in adult spinal deformity(ASD). Methods. Patients with baseline (BL) and 2-year (2Y) data were included. Disability was ranked according to BL ODI into quintiles: Q1 (lowest ODI score) to Q5 (highest ODI score). Adjusted logistic regression analyses evaluated the likelihood of reaching ≥1 MCID in SRS-22 Pain, SRS-22 Activity, and SF-36 PCS at 2Y across disability groups Q1–Q4 with respect to Q5. Sensitivity tests were performed, excluding patients with any “0” Schwab modifiers at BL. Results. Compared to patients in Q5, odds of reaching MCID in SRS-22-Pain at 2Y were significantly higher for those in Q1 (OR: 3.771), Q2 (OR: 3.006), and Q3 (OR: 2.897), all P<0.021. Similarly, compared to patients in Q5, odds of reaching MCID in SRS-22-Activity at 2Y were significantly higher for those in Q2 (OR: 3.454) and Q3 (OR: 2.801), both P<0.02. Lastly, compared to patients in Q5, odds of reaching MCID in SF-36-PCS at 2Y were significantly higher for patients in Q1 (OR: 5.350), Q2 (OR: 4.795) and Q3 (OR: 6.229), all P<0.004. Conclusions. This study found that patients presenting with moderate disability at BL (ODI<40) consistently surpassed HRQL outcomes as compared to those presenting with greater levels of disability. We propose that a baseline ODI of 40 represents a disability threshold within which operative intervention maximizes patient reported outcomes. Furthermore, delaying intervention until patients progress to severe disability, may limit benefits of surgical correction in ASD patients. Level of Evidence. III