Validity and reliability of a new short verbal rating scale for stress for use in clinical practice

Stress is a common experience that affects the body and the brain in many ways. It can sometimes be of interest in research and clinical practice to measure the intensity of single stress reactions. For example, data on intensity can be important for understanding factors such as stress-related behaviour and pain and for a better understanding of physiological stress reactions in hormones, muscles and the circulatory system. Stress can be measured in a number of ways, including shifts in the production of cortisol and adrenaline and in skin conductance. But performing such tests is not without its difficulties, and the results can be hard to evaluate. An alternative to physiological measurements is verbal instruments. According to a search at PubMed in November 2013 and discussions with colleagues, those that have been developed so far involve many issues and, as a result, take time to answer. Two examples are the State-Trait Anxiety Inventory for Children (STAIC) with 20 items (1) and the Multidimensional Anxiety Scale for Children (MASC) with 37 items (2). However, there is a need for an instrument that assesses the intensity of single stress attacks in a simple, valid and reliable way, and we have not been able to find one. A short verbal rating scale for stress (VRSS), reporting recent or present experience of stress and easy to use in clinical routine settings and research, would meet this demand. An important issue in the development of such an instrument is how it operates, including the theoretical framework, the context of the application and the selection of optimal responses. These are also the key factors that define how we measure the quality of an instrument (3). Instruments capturing stress should be valid and reliable, easy to understand and use and have good compliance. The aim of this study was therefore to test a new VRSS developed by one of the authors. The material consisted of two samples. The first included 28 children, seven boys and 21 girls, with a mean age of 12.6 years (range: seven to 16) visiting a clinic for recurrent pain. The second sample consisted of 34 children, 15 boys and 19 girls, aged 11.3 years (range: eight to 16). Fifteen of them were recruited from the same clinic as the first sample, and 19 were recruited from a clinic for children with needle phobias. All the children indicated that they knew what stress was and all of them were able to describe their own feeling of stress. After a brief talk about the child’s stress reaction, the child was asked to describe their latest stressful experience in a few words. For the children attending the pain clinic, this incident had happened during the last few days and not longer than a week ago. The children with needle phobias described the stress they felt when they came in for a practice injection. The researchers used a new verbal rating scale for stress (VRSS), based on a scale of zero to five, that had been developed, tested and retested in school age children, in collaboration with two psychologists. The VRSS provides an easy to understand scale that offers the children alternative responses when it comes to describing an increase in their stress levels (see Appendix). Validity of a scale is best evaluated by comparing it with a validated scale measuring the same parameter. But such a scale could not be found, so we measured the agreement between the VRSS and a visual analogue scale (VAS) measuring the same phenomenon. This was done in both groups. The child was asked to choose one of six alternatives on the VRSS to report how strong the latest experienced stress (VRSS1) was and to report the same experience on a visual analogue scale (VAS1) with the written anchors ‘no stress’ and ‘the worst known stress. ’