Responsiveness of common outcome measures for patients with low back pain.

STUDY
DESIGN: A prospective cohort study assessing the responsiveness of two disease-specific questionnaires and a generic health questionnaire for patients with low back pain and sciatica.
OBJECTIVES: To compare the responsiveness of the eight scales and two summery scales of the SF-36 questionnaire with that of the Oswestry Disability Index and Low Back Outcome Score questionnaires. SUMMARY OF BACKGROUND DATA: Evaluation of treatment outcome is being determined more frequently from a patient's perspective, particularly the impact treatment has on current health status.
METHODS: Patients were recruited from two orthopedic back pain clinics in a tertiary hospital. Patients completed the pretreatment questionnaire 1 month before treatment and follow-up questionnaires a minimum of 2-6 months after treatment. Patients undergoing surgery were also observed for a minimum of 2 years.
RESULTS: Overall, the Oswestry Disability Index was most responsive; however, individual scales from the SF-36 questionnaire showed equal or greater sensitivity to change than the Oswestry Disability Index in each of the patient subgroups. The SF-36 Role Physical scale was prone to floor effects (a high percentage of respondents score zero), and the change scores from the SF-36 Role Emotional scale varied by 100 points in either direction in each of the patient subgroups.
CONCLUSION: Responsiveness varied according to which method was used in its calculation. The responsiveness of the SF-36 questionnaire shows that it can be a useful adjunct in the assessment of patients with low back pain when combined with disease-specific questionnaires.