Differentiation of pain-related functional limitations in surgical patients with lumbar spinal stenosis (LSS) using the Oswestry Disability Index: a Canadian Spine Outcomes and Research Network (CSORN) study

BACKGROUND CONTEXT The Oswestry Disability Index (ODI) is the most commonly used outcome measure of functional outcome in spine surgery. The ability of the ODI to differentiate pain related functional limitation specifically related to degenerative lumbar spinal stenosis (LSS) is unclear. PURPOSE The purpose of this study was to determine the ability of the functional subsections of the ODI to differentiate the specific patient limitation(s) from symptomatic LSS and the functional impact of surgery. STUDY DESIGN Analysis of prospectively collected data from the Canadian Spine Outcomes and Research Network (CSORN). PATIENT SAMPLE A total of 1,497 lumbar spinal stenosis patients with a dominant complaint of neurogenic claudication, radiculopathy or back pain were identified in the CSORN registry. OUTCOME MEASURES The ODI questionnaire version 2.0 was assessed as an outcome measure. METHODS The difference at baseline and the pre-to-post (1-year) surgical change of the ODI individual questions was assessed. Analysis of variance, two-tailed paired sample Student t test were used for statistical analysis. Cohen d was used as an index of effect size, defined as "large" when d ≥0.8. RESULTS The mean age at surgery was 65 (±11) years and (50.8%) of the patients were female. Preoperatively, highest functional limitations were noted for standing, lifting, walking, pain intensity and social life (mean 3.2, 2.9, 2.5, 2.9, 2.5 respectively). At 1-year follow-up, overall there was a significant improvement in all individual questions and the overall ODI (all p