The minimum clinically significant difference in patient-assigned numeric scores for pain

Abstract

Objective: To determine the minimum clinically significant difference (MCSD) in patient-assigned, 11-point numeric rating scale (NRS-11) scores for pain and to determine if the MCSD varied with demographic characteristics.

Methods: Eligible emergency department patients presenting with pain were asked to rate their pain on the NRS-11 every 20 minutes. Subjects compared pain intensity by choosing from the following verbal descriptor responses: "a lot more," "a little more," "about the same," "a little less," or "a lot less" pain. The MCSD was defined as the difference between scores rated "a little more" or "a little less" severe.

Results: Three hundred fifty-four subjects were enrolled. The MCSD was 1.39 +/- 1.05 (95% confidence interval, 1.27-1.51). No statistically significant difference based on sex or pain etiology was noted.

Conclusions: Findings suggest that a change of 1.39 +/- 1.05 (95% confidence interval, 1.27-1.51) on the NRS-11 is clinically significant when measuring pain.