Objective: To compare the responsiveness of three pain scales.
Design: Longitudinal prospective single cohort.
Setting: Chiropractic college outpatient clinic.
Subjects: Seventy-nine new patients.
Intervention: Treatment of painful complaint by senior student interns under supervision of clinical tutors.
Outcome measures: Pain intensity using the visual analogue scale (VAS), the verbal rating scale (VRS) and the 11-point numerical rating scale (NRS).
Results: Mean usual levels of pain were consistently higher than those of current pain. Asking patients to report their current pain levels showed the NRS to be the most responsive of the measures (effect size = 0.86) compared with the VAS (effect size = 0.77) and the VRS (effect size = 0.76). When asking patients to report on their usual level of pain, the responsiveness of all the pain scales was enhanced (effect size = 1.34, 1.34 and 1.12 for the NRS, VAS and VRS, respectively).
Conclusion: Given the relative ease of use and scoring of the 11-point NRS, and the obvious advantages of using responsive evaluative measures, this scale is recommended for pain intensity measurement in most types of outcome studies. Furthermore, asking patients to report their usual pain levels, rather than current levels, enhances the responsiveness of the measures and is a more representative perspective of their pain experience. The findings of this study have important implications for investigators who wish to select the most appropriate pain scale for use an outcome measure in treatment evaluative trials.