Validity and reproducibility of self-report measures of walking capacity in lumbar spinal stenosis.

Abstract

Measurement (validity) study. Examine validity and reproducibility of self-report measures of walking capacity for use in patients with lumbar spinal stenosis (LSS). Treatment outcomes in patients with LSS are often determined using data from self-report questionnaires. Despite some validity evidence available to support the use of self-report instruments in the evaluation of walking capacity in LSS, it is not certain that the construct being tapped using any of the self-report measures is, in fact, walking capacity. Validity of the Physical Function Scale of the Swiss Spinal Stenosis Questionnaire, the Oswestry Disability Index (ODI), self-predicted walking capacity (distance in meters) and a number of single item walking capacity questions was evaluated through comparison with a criterion measure of walking capacity, the Self-Paced Walking Test, in patients with LSS. Test-retest reproducibility was also examined for each of the self-report measures. Subjects included 49 patients (65.8 ± 10.0 years of age) with LSS confirmed on imaging and by a spine specialist surgeon. The measures found to be most highly associated with the criterion Self-Paced Walking Test were the walking distance item from the ODI (r = 0.83) and self-reported walking capacity in meters (with the aid of a distance reference) (r = 0.80). Reported walking capacity in meters had the lowest test-retest reproducibility (intraclass correlation coefficient = 0.65) of the measures studied. This study provides new information to help guide health professionals and researchers in the selection of appropriate outcome tools when examining walking in an LSS population. Study results support the use of the Physical Function Scale, self-reported walking distance, and the walking specific items from the ODI and the Physical Function Scale.