- OBJECTIVE: To determine whether the measurement properties of the Back Pain Functional Scale (BPFS) are superior to the Roland-Morris Questionnaire (RMQ). METHODS: The BPFS and RMQ were administered on multiple occasions to 153 patients with low back pain attending physical therapy. Eleven Canadian clinics and 8 American clinics participated in the study. Ceiling effects, internal consistency, test-retest reliability, cross sectional discriminant validity, and sensitivity to change were investigated. Error estimates in scale points were obtained. RESULTS: A ceiling effect was noted for 6 patients' RMQ scores compared to 3 patients' BPFS scores. Internal consistency for the RMQ and BPFS were 0.87 and 0.93, respectively. The error (95% CI) for a patient's score was +/- 15.5% of the scale range for the RMQ and +/- 10.5% for the BPFS. The test-retest reliability was 0.79 for the RMQ and 0.82 for the BPFS. The error associated with a patient's change score (95% CI) was 27.7% of the scale range for the RMQ and 22.2% for the BPFS. The measures showed similar levels of discriminant validity with respect to physical findings, work status, and education level. The BPFS was more adept at detecting different amounts of change in patients with back pain of less than 2 weeks' duration compared to patients with back pain of 2 or more weeks' duration. CONCLUSION: The BPFS is a competitive functional status measure for patients with low back pain.