Psychometric Characteristics and Clinical Usefulness of Physical Performance Tests in Patients With Low Back Pain

Abstract

STUDY DESIGN: The psychometric properties and clinical use of a battery of physical performance measures were tested on 44 patients with low back pain and 48 healthy, pain-free control subjects. OBJECTIVES: Reliability, validity, and clinical use of nine physical performance measures were evaluated. SUMMARY OF BACKGROUND DATA: Although physical performance measures have potential use in evaluation, treatment planning, and determination of treatment outcome, there is sparse systematic investigation of their reliability, validity, and clinical use. METHODS: Forty-four subjects with low back pain and 48 healthy pain-free subjects participated. The following physical performance measures were tested: distance walked in 5 minutes; 50-foot walk at fastest speed; 50-foot walk at preferred speed; 5 repetitions of a sit-to-stand task; 10 repetitions of a repeated trunk flexion task; timed up-and-go task; unloaded forward reach task; loaded forward reach task; and Sorensen fatigue test. Subjects were assessed twice on 2 days. RESULTS: All measures had excellent intertester reliability (intraclass correlation coefficient [ICC]1,1 > 0.95). Test-retest (within session) reliability was adequate for all measures (ICC1,1 > 0.83) except repeated trunk flexion (ICC1,1 > 0.45) in the low back pain group. Test-retest (day-to-day) reliability ranged between 0.59 and 0.88 in the low back pain group and between 0.46 and 0.76 in the control group. Day-to-day reliability improved when the averages of two trials of repeated trunk flexion and sit-to-stand were used (0.76-0.91 low back pain group and 0.62-0.89 control group). Results of a multivariate analysis of variance showed a significant effect of group (F10,65 = 3.52, P = 0.001). Results of univariate analyses showed significant group differences on all measures except the 50-foot walk at preferred speed and unloaded forward reach. Self-report of disability was moderately correlated with the performance tasks (r = 0.400 to -0.603). CONCLUSIONS: The results provide support for the use of these physical performance measures as a complement to patient self-report.