Physical functioning: Self-report and performance measures are related but distinct

• Published in: Spine (Philadelphia, Pa. 1976) Pa. 1976), 2003-10, Vol.28 (20), p.2407-2413
• Main Authors: WITTINK, Harriët, ROGERS, William, SUKIENNIK, Andrew, CARR, Daniel B
• Format: Article
• Language: English
• Subjects: Activities of Daily Living; Adult; Biological and medical sciences; Chronic Disease; Cross-Sectional Studies; Disability Evaluation; Diseases of the osteoarticular system; Diseases of the spine; Exercise Test; Female; Heart Rate; Humans; Low Back Pain - physiopathology; Low Back Pain - psychology; Male; Medical sciences; Mental Health; Middle Aged; Quality of Life; Reproducibility of Results; Surveys and Questionnaires
• ISSN: 0362-2436; 1528-1159
• DOI: 10.1097/01.brs.0000085304.01483.17

Cross-sectional study of 63 patients with chronic low back pain (CLBP). To determine the relationship between the SF-36 physical functioning (PF) scale and physical performance on a modified symptom limited treadmill test, and to determine the effect of disability status and SF-36 mental health (MH) scores on self-reported physical functioning and on physical performance. Patients with CLBP report low levels of physical functioning. Because self-report measures are influenced by psychosocial factors, such as disability and low MH, a common recommendation is to supplement self-report with objective or physical performance testing. Little information exists regarding whether performance testing is also influenced by disability and low MH. Patients completed the SF-36 and performed a maximal, symptom-limited, modified treadmill test. Total walking time and heart rate on the treadmill were registered. The effects of disability and low MH on self-report and performance testing were calculated by unpaired Student's t-testing and effect size estimation. A strong relationship between the PF scale of the SF-36 and treadmill walking time was found, but there was little evidence of overlap between these physical functioning domains. Both disability status and low MH had a much larger effect on self-report measures than on physical performance. Self-report measurements and performance-based assessments provide information about distinct, although related, domains of physical functioning. Disability and low MH are associated with lower SF-36 PF scores. Our results confirm that self-report measures require supplementation with objective performance testing to provide optimal assessment for patients with CLBP.