Reliability of rating low back pain with a visual analogue scale and a semantic differential scale

Abstract

Pain rating scales, such as the Visual Analogue Scale (VAS) and the Verbal Rating Scale (VRS) are important tools for assessing patients' symptom status. For a non-English speaking patient, VRS could pose a problem as a result of language barrier. The objective of this study was to determine the intra-class and inter-class correlations of VAS and a Semantic Differential Scale (SDS) in patients with low back pain. 25 patients with chronic low back pain were purposively selected for the study. Two testers (1 and 2) independently rated the pain experienced by the patients when asked to bend forward and hold on when pain was either exacerbated or aggravated. Finger-to-floor distance (FFD) was taken, as a measure of flexion of the spine, for each patient. Pain was rated using VAS and SDS. Our results showed strong intra-tester correlations between VAS and SDS of each tester (p < .05), and strong inter-tester correlations for VAS and for SDS (p < .05). The result of using two-way ANOVA showed that there was no significant difference in pain ratings with VAS by tester-1, VAS by tester-2, SDS by tester-1, and SDS by tester-2. F-ratio was not significant (p > .05). There was no significant difference between FFDs by the two testers (p > .05). Our results suggest that the two scales are reliable and valid for clinical rating of low back pain. Further studies with larger samples and using other movements of the spine are suggested.