Relationship of the Pain Disability Index (PDI) and the Oswestry Disability Questionnaire (ODQ) with three dynamic physical tests in a group of patients with chronic low-back and leg pain

Abstract

Objective: To determine the relationship between overall disability in daily activities, assessed with the Pain Disability Index (PDI) and the Oswestry Disability Questionnaire (ODQ), and impaired performance on three physical tests in patients with chronic low-back pain.

Design and subjects: The PDI and ODQ were administered in a cross-sectional study, before beginning a back rehabilitation program, to 45 patients with low-back pain of > or = 3 months' duration, with or without radiation to the legs. All patients also performed repetitive sit-up, arch-up, and squatting tests.

Setting: Tertiary care center.

Results: Modestly significant (p < 0.05) or significant (p < 0.01) inverse correlations (Pearson's r = 0.30-0.41) were noted between the PDI and the ODQ and all three physical performance tests. When normative data were used, the correlation (Spearman's rs = -0.45) between PDI and the squatting test remained significant (p < 0.01), whereas it was modestly significant (rs = -0.33, p < 0.05) between the ODQ and squatting test and between the PDI and arch-up test (rs = -0.35, p < 0.05). Compared with patients presently working, those on sick leave had significantly higher scores on the PDI and ODQ (Wilcoxon's two-sample test: p < 0.001) and also significantly worse performance on all physical tests (p < 0.001).

Conclusions: The PDI and ODQ, as measures of self-perceived disability, and impaired performance on repetitive squatting, arch-up, and sit-up tests, as measures of physical capability, show some overlap in low-back-pain patients. Both types of disability measures are clearly influenced by the patient's work status.