Correlation of change in visual analog scale with pain relief in the ED

Objectives To evaluate the validity of change in visual analog Scale (VAS) as a measure of pain relief using a verbal descriptor Scale (VDS) of change in pain. Methods A prospective observational study of emergency department patients measured pain with VAS and recorded verbal report of change in pain. Results One thousand four hundred ninety patients yielded 1999 comparisons between change in VAS and VDS. Correlation of change in VAS and VDS of change in pain was ρ = 0.667 (P < .001). A wide range of change in VAS, large standard deviations for the mean change in VAS, and discordance in the direction of change in VAS were present within each verbal descriptor category. Conclusions Change in VAS is moderately correlated with a VDS of change in pain. Wide variability in change in VAS and discordance with a VDS demonstrate that change in VAS is not a valid indicator of pain relief for individual patients.