CLINICAL-SIGNIFICANCE OF REPORTED CHANGES IN PAIN SEVERITY

Study objective: To determine the amount of change in pain severity, a s measured by a visual analog scale, that constitutes a minimum clinic ally significant difference. Methods: Patients 18 years of age or olde r who presented with acute pain resulting from trauma were enrolled in this prospective, descriptive study. The setting was an urban county hospital emergency department with a Level I trauma center. In the cou rse of a brief interview, patients were asked to indicate their curren t pain severity with a single mark through a standard 1 OO-mm visual a nalog scale. At intervals of 20 minutes for ?he next 2 hours, patients were asked to repeat this measurement and, in addition, to contrast t heir present pain severity with that at the time of the previous measu rement. They were to indicate whether they had ''much less,'' ''a litt le less,'' ''about the same,'' a little more,'' or ''much 1 more'' pai n. All contrasts were made without reference to prior visual analog sc ale measurements. A maximum of six measurements of pain change were re corded per patient. Measurements ended when the patient left the ED or when the patient reported a pain score of zero. The minimum clinicall y significant change in visual analog scale pain score was defined as the mean difference between current and preceding visual analog scale scores when the subject noted a little less or a little more pain. Res ults: Forty-eight subjects were enrolled, and 248 pain contrasts were recorded. Of these contrasts, 41 were rated as a little less and 39 as a little more pain. The mean difference between current and preceding visual analog scale scores in these 80 contrasts was 13 mm (95% confi dence interval, 10 to 17 mm).Conclusion: The minimum clinically signif icant change in patient pain severity measured with a 100-mm Visual an alog scale was 13 mm. Studies of pain experience that report less than a 13-mm change in pain severity, although statistically significant, may have no clinical importance.