To establish the reliability with which tenderness could be evaluated in patients with chronic myalgias, using dolorimetry and palpation.
Three blinded examiners using pressure dolorimetry and digital palpation compared 19 paired tender points and 8 paired control points in 4 matched groups of 6 patients with fibromyalgia (FM), myofascial pain, pain controls, and healthy controls.
Good interrater and test-retest reliability were found for dolorimetry scores. There were significant differences in tenderness ratings by dolorimetry between the diagnostic groups, with the patients with FM and myofascial pain having the greatest tenderness, the normals having the least tenderness, and the pain controls having tenderness levels midway between the patients with FM or myofascial pain and the normals. In all patients, control points had higher pain thresholds than tender points. One-third of patients with localized pain complaints demonstrated a significant relationship between region of clinical pain complaint and measured tenderness thresholds by dolorimetry. In ratings of tenderness by digital palpation, there was very good intrarater reliability over 26 of 27 paired points, and good interrater reliability at 75% of the points. One-half of patients with localized pain complaints demonstrated a significant relationship between region of clinical pain complaint and number of tender points by palpation.
Both dolorimetry and palpation are sufficiently reliable to discriminate control patients from patients with myofascial pain and FM, but may not discriminate patients with myofascial pain from those with FM. Neither method appears to correlate well with the location of the clinical pain complaint, regardless of diagnosis.