Responsiveness of Common Outcome Measures for Patients With Low Back Pain

Abstract

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. To compare the responsiveness of the eight scales and two summary scales of the SF-36 questionnaire with that of the Oswestry Disability Index and Low Back Outcome Score questionnaires. Evaluation of treatment outcome is being determined more frequently from a patient’s perspective, particularly the impact treatment has on current health status. 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. 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. 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. [Key words: Low Back Outcome Score, low back pain, Oswestry Disability Index, outcome measures, responsiveness, SF-36]