Reliable and valid measures of pain intensity are needed to accurately evaluate the efficacy of pain treatments. Perhaps with the exception of faces pain intensity scales, which are thought to reflect both pain intensity and pain affect, the other most commonly used pain intensity scales—Numerical Rating Scales (NRSs), Visual Analog Scales, and Verbal Rating Scales (VRSs)—are all thought to reflect primarily pain intensity or the magnitude of felt pain. However, to our knowledge, this assumption has not been directly tested for VRSs.
We evaluated whether VRS pain severity ratings are influenced by pain beliefs, catastrophizing, or pain interference over and above any effects of pain intensity, as measured by a NRS, in 4 samples of individuals with physical disabilities and chronic pain.
As hypothesized, and while controlling for pain intensity as measured by a NRS, higher scores on factors representing pain interference with function, pain catastrophizing, and a number of pain-related beliefs were all associated with a tendency for the study participants to rate their pain as more severe on a VRS.
These findings indicate VRSs of pain severity cannot necessarily be assumed to measure only pain intensity; they may also reflect patient perceptions about pain interference and beliefs about their pain. Clinicians and researchers should take these findings into account when selecting measures and when interpreting the results of studies using VRSs as outcome measures.