Responsiveness of pain and disability measures for chronic whiplash

Study Design. Cohort study. Objective. To evaluate the responsiveness of common pain and disability measures in a cohort of patients with chronic whiplash. Summary of Background Data. Pain and disability are routinely measured in clinical practice and clinical research. However, to date, a head-to-head comparison of competing measures for whiplash patients has not been performed. Methods. Pain (pain intensity, bothersomeness, and SF-36 bodily pain score) and disability (Patient Specific Functional Scale, Neck Disability Index, Functional Rating Index, Copenhagen Scale, and SF-36 physical summary) measures were completed by 132 patients with chronic whiplash at baseline and then again after 6 weeks together with an 11-point global perceived effect scale. Internal responsiveness was evaluated by calculating effect sizes and standardized response means, and external responsiveness by correlating change scores with global perceived effect scores and by ROC curves. Results. The ranking of responsiveness was consistent across the different analyses. Pain bothersomeness was more responsive than pain intensity, which was more responsive than the SF-36 pain measure. The Patient Specific Functional Scale was the most responsive disability measure, followed by the spine-specific measures, with the SF-36 physical summary measure the least responsive. Conclusion. Pain bothersomeness and the Patient Specific Functional Scale provide the most responsive measures of pain and disability, respectively, in patients with chronic whiplash.