A clinical comparison of two pain scales: correlation, remembering chronic pain, and a measure of compliance

Abstract

Fifteen chronic pain patients rated their pain intensity on both a visual analogue scale and a verbal scale so that comparisons between the scales could be made for each subject. Compliance to fill in the rating blanks and the remembering of pain intensity were also studied. Subjects first made a pre-baseline estimate of their pain and then they rated their pain throughout a baseline and treatment period averaging 5 weeks. Four to 9 weeks after baseline, subjects were asked to remember how much pain they had had at baseline and to confidentially provide ratings concerning their compliance. Results indicated that two-thirds of the individual subjects had significant correlations between the scales with a mean of 0.68. The one-third of the subjects who did not have significant correlations also had significantly less variability in their ratings than did subjects with significant correlations. This low level of variability may account for the lack of a significant correlation between the scales for these subjects. Discrepancies between actual baseline and remembered pain ratings were observed on both rating scales, but the visual analogue scale produced significantly greater discrepancies than the verbal scale. This was mainly because subjects tended to overestimate their baseline pain on the visual analogue scale, while discrepancies on the verbal scale were in both directions (overestimations, underestimations) when taken as a group.(ABSTRACT TRUNCATED AT 250 WORDS)