Summary: 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.
Methods: 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.
Results: 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.
Discussion: 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.
*Department of Rehabilitation Medicine, University of Washington, Seattle, WA
†Unit for the Study and Treatment of Pain—ALGOS
‡Department of Psychology, Research Center for Behavior Assessment (CRAMC)
§Institut d’Investigació Sanitària Pere Virgili
∥Universitat Rovira i Virgili-Fundación Grünenthal, Catalonia, Spain
This research was supported in part by grant number P01 HD33988 from the National Institutes of Health, National Institute of Child Health and Human Development (National Center for Medical Rehabilitation Research), Rockville, MD. Financial support for this project was provided by grants from Spanish Ministry of Economy and Competitiveness (PSI2012-32471, PSI2015-70966-P), Madrid, Spain; Obra Social de Caixabank, Barcelona, Catalonia, Spain, and RecerCaixa, Barcelona, Catalonia, Spain, awarded to J.M. J.M.’s work is supported by the Institució Catalana de Recerca i Estudis Avançats (ICREA-Acadèmia), Barcelona, Catalonia, Spain, and Fundación Grünenthal, Madrid, Spain. R.d.l.V.’s work is supported by a Beatriu de Pinós Postdoctoral Fellowship (2014 BP-A 00009) granted by the Agency for Administration of University and Research Grants (AGAUR), Barcelona, Catalonia, Spain. Grant R2B from Universitat Rovira i Virgili, Tarragona, Catalonia, Spain, provided travel support. S.G. is supported by a doctoral grant from MINECO, Madrid, Spain. The authors declare no conflict of interest.
Reprints: Mark P. Jensen, PhD, Department of Rehabilitation Medicine, University of Washington, P.O. Box 359612, Harborview Medical Center, 325 Ninth Avenue, Seattle, WA 98104 (e-mail: firstname.lastname@example.org).
Received March 21, 2016
Received in revised form October 26, 2016
Accepted August 17, 2016