One of the 2 classification criteria for fibromyalgia (FM) is the presence of tender points on specific anatomic sites. It has been established that these tender points reflect a state of generalized allodynia (defined as pain resulting from a stimulus that does not normally provoke pain). Patients with FM often describe pain elicitation during blood pressure testing (sphygmomanometry).
The objective of this study was to define if a universally used clinical test, sphygmomanometry, is helpful in the identification of patients with FM.
The authors conducted a prospective multicenter study in 3 different public rheumatology outpatient services. Each center studied 20 patients with FM, 20 with rheumatoid arthritis, 20 with osteoarthritis, and 20 healthy individuals. The following question was asked of each participant: "When I take your blood pressure, tell me if the cuff's pressure brings forth pain." The blood pressure cuff was inflated at an approximate rate of 10 mm Hg per second up to 180 mm Hg or to the point when pain was elicited.
Sixty-nine percent of patients with FM had sphygmomanometry-evoked allodynia in contrast to 10% of patients with osteoarthritis, 5% with rheumatoid arthritis, and 2% of healthy individuals (P < 0.001). The mean blood pressure value at which allodynia was elicited was lower in patients with FM (143 +/- 40 mm Hg) when compared with the other 3 groups (176 +/- 11 mm Hg) or higher (P < 0.001). In patients with FM, there was a significant negative correlation between the blood pressure value at which allodynia developed and total Fibromyalgia Impact Questionnaire (FIQ) score, number of tender points, and the FIQ visual analog scales for pain intensity and fatigue (P < 0.05). The test yields a diagnostic sensitivity for FM of 0.7, specificity 0.96, positive predictive value 0.86, and negative predictive value 0.91.
In this developmental study of patients attending rheumatology clinics, the generation of pain during blood pressure testing was strongly associated with the diagnosis of FM. This robust linkage probably reflects a tautologic phenomenon. A sine qua nonelement for FM diagnosis is the presence of tender points in discrete anatomic sites. These tender points in turn reflect a state of generalized mechanical allodynia that can be locally elicited by the cuff pressure during blood pressure testing. Sphygmomanometry is a simple bedside test that may be useful in the recognition of patients with FM. Blood pressure testing is a universal procedure in all clinical environments. Based on our results, we suggest searching for FM features in any person who has sphygmomanometry-evoked allodynia.