Do Past Pain Events Systematically Impact Pain Ratings of Healthy Subjects or Fibromyalgia Patients?

We previously reported that 3 different electronic visual analogue and numerical pain scales are useful in providing refined capacity to discriminate discrete levels of pain intensity. Using the same subjects and scales, we now investigated whether pain scaling is influenced by past pain events and by recalled memories of these events in the rating of pain. Normal control subjects (NC: 19 male, 30 female) and female fibromyalgia (FM) (n = 17) patients received 5-second suprathres-hold heat stimuli (45-49 degrees C) to both forearms. The participants rated these experimental heat stimuli using the previously described electronic pain scales. Subsequently, they were asked to report whether they used any prior pain experiences during the process of rating their pain. Out of 49 NC, only 6 females (12.2%) and 7 males (14.3%), and out of 17 FM patients, only 3 females (17.6%) stated that they had used past pain experiences during scaling. Notably, pain ratings of experimental heat stimuli did not statistically differ between subjects who used past pain experiences during scaling as compared to those who did not. Furthermore, ratings of their most severe past pains were not significantly correlated with ratings of experimental pain stimuli. These results do not provide support for the strong assertion that pain rating scales are elastic, ie, being used differently depending on the severity of past pain events such as childbirth. Perspective: Less than 25% of subjects used memories of past pain events during pain scaling. In addition, if they were used, these pain memories did not influence pain scaling with electronic eVAS and eNUM scales. Thus, use of these scales allows reliable comparisons of experimental and clinical pain ratings within and between subjects. (C) 2010 by the American Pain Society