Clinically significant changes in pain along the visual analog scale

We sought to test the hypothesis that the change in visual analog scale (VAS) associated with a clinically significant change in pain is related to the initial VAS score.

A convenience sample of adults with isolated extremity trauma was enrolled. A VAS score was obtained on entry into the study. Descriptions of change in pain ("lot less," "little less," "about the same," "little more," or "lot more") and VAS scores were then obtained every 30 minutes until the patient was free of pain or discharged or a total of 2 hours had passed. Patients were divided into 3 cohorts on the basis of the initial VAS score: VAS score of less than 34, VAS score of 34 to 66, and VAS score of 67 or greater. The absolute values of VAS changes associated with pain descriptions of a "little less" or "little more" (defined as clinically significant), "about the same" (defined as clinically insignificant), and "lot less" or "lot more" were calculated.

The change in VAS associated with clinically significant changes in pain in the cohort with VAS scores of less than 34 was 13+/-14 (mean+/-SD), which was significantly lower than that of the cohort with VAS scores of 67 or greater (28+/-21). There was no statistically significant difference in clinically significant changes in pain between the middle cohort and either the upper or lower cohorts (P =.07 and P =.29, respectively). There was no significant change in VAS for clinically insignificant changes in pain among the 3 cohorts (3+/-4, 6+/-6, and 8+/-16, respectively).

Patients with greater pain require a greater change in VAS score to achieve clinically significant pain relief.