Sphygmomanometry-evoked allodynia in chronic pain patients with and without fibromyalgia

BACKGROUND: Fibromyalgia is a chronic pain syndrome that affects about 2% of the U.S. general population, with greater prevalence among women (3.5%) than men (0.5%). Previous research results suggest that the experience of pain (allodynia) upon sphygmomanometry may indicate the presence of fibromyalgia. OBJECTIVE: The aim of this study was to confirm these findings in patients with fibromyalgia and other chronic pain conditions and evaluate the use of sphygmomanometry as a potential screening tool for the identification of patients with fibromyalgia. METHODS: A total of 150 people participated in this multicenter, cross-sectional observational study. The study included a physician-conducted evaluation to determine if the participant met the American College of Rheumatology (ACR) 1990 diagnostic criteria for fibromyalgia. The presence of sphygmomanometry-evoked allodynia was assessed during a seated cuff pressure inflation that was repeated three times on each arm. Each site was provided a sphygmomanometer to ensure standardization, and the pressure of the cuff at the moment of pain initiation was recorded. If the patient did not indicate pain prior to 180 mmHg, then the inflation was stopped, a notation of no pain was made, and a cuff pressure of 180 mmHg was recorded. The mean of the six cuff pressure measurements was used for the analyses. Logistic regression was performed to analyze the relationship between sphygmomanometry-evoked allodynia and fibromyalgia. RESULTS: The evaluable sample was 148 (one participant had too large an arm circumference for the sphygmomanometer and another did not receive the clinician evaluation of ACR-determined fibromyalgia diagnosis). Over half of the participants were determined to have an ACR diagnosis of fibromyalgia. Of these, 71 (91%) were women and had an average age of 54 years. Of the 70 participants with no fibromyalgia diagnosis, 42 (60%) were women and also had an average age of 54 years. Sixty-one (78%) of the fibromyalgia participants, compared with 25 (36%) of those with no fibromyalgia diagnosis, reported sphygmomanometry-evoked allodynia. The participants with fibromyalgia reported pain ata lower cuff pressure compared with those without fibromyalgia (132 mmHg vs. 166 mmHg, p < .01). The logistic regression showed that sphygmomanometry-evoked allodynia predicted an ACR-determined FM diagnosis (χ(2) = 19.4, p < .01). DISCUSSION: These findings support previous research suggesting that patients who report pain upon sphygmomanometry may warrant further evaluation for the presence of fibromyalgia.