THE MINIMUM CLINICALLY IMPORTANT DIFFERENCE IN PHYSICIAN-ASSIGNED VISUAL ANALOG PAIN SCORES

Objective: To determine the minimum clinically important difference in physician-assigned visual analog scale (VAS) pain scores. Methods: Ph ysicians attending emergency medicine didactic conferences were enroll ed in this descriptive study. The subjects sequentially reviewed 11 wr itten scenarios describing patients in moderate to severe pain. The su bjects rated their perceptions of each patient's pain on a 100-mm VAS, then contrasted this pain with that of the previous patient scenario. For these contrasts, the subjects chose one of five responses: ''much less,'' ''a little less,'' ''about the same,'' ''a little more,'' or ''much more'' pain. The minimum clinically important difference was de fined as the difference between scores for scenario pairs in which one patient's pain was rated ''a little less'' or ''a little more'' sever e. Results: There were 230 comparisons by 23 health professionals. Of these, 64 were judged ''a little less,'' and 56 ''a little more,'' pai nful. These 120 comparisons, with their pain score differences, were u sed to determine the minimum clinically important difference. Pain jud ged to be ''a little less'' or ''a little more'' severe was associated with a mean difference in VAS scores of 18 mm (95% Cl 16-20 mm), corr esponding to a decrement of 23% (95% Cl 20-26%) from the more painful scenario. Conclusions: Pain research outcomes involving a <18-mm diffe rence, or a 23% decrement in physician-assigned VAS pain scores, altho ugh statistically significant, may have little clinical importance.