Trends of the Oswestry Disability Index in Adult Spinal Deformity Patients: A 3-Year Study.

Background: Patients with adult spinal deformity (ASD) undergoing operative treatment may have varying degrees of improvement in patient-reported outcomes. The Oswestry Disability Index (ODI) assesses improvement in quality of life. We aim to measure longitudinal outcomes of ODI scores over 3 years to determine if early ODI scores predict late ODI scores and to analyze longitudinal changes in ODI scores.
Methods: Two hundred thirty-five patients above the age of 18 who underwent surgical correction of ASD at a single institution from 2016 to 2021 and completed ODI questionnaires at follow-up appointments met inclusion criteria. ODI scores were included from follow-up visits at 0 months (immediately postoperative) and within ±1 month of 3, 6, 12, 18, 24, 30, and 36 months. Percent change in ODI from 0 months was calculated, and unpaired t tests were conducted.
Results: ODI scores increased by 8.8% immediately postoperatively, and the percent change from preoperative ODI scores at each subsequent visit were as follows: -11.1% at 3 months, -21.4% at 6 months, -25.4% at 12 months, -28% at 18 months, -31.3% at 24 months, -25.7% at 30 months, and -36.5% at 36 months. ODI scores at each follow-up visit showed significant improvement from baseline (P < 0.001). There was an improvement in scores from 3 to 6 months (P = 0.04), but no significant difference in 6-month interval visits following 6 months.
Conclusions: Our results demonstrate a significant and sustained improvement in ODI scores over 3 years following surgical correction of ASD. ODI scores were stable after 6 months, indicating that ODI scores at 6 months may be predictive of scores out to 3 years postoperatively. Examining individual components of ODI sub-scores and comparing ODI results to other PROMs are critical to better assess long-term outcomes in ASD.
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