OBJECTIVE: To investigate the relation between measures of pain
threshold and symptoms of distress to determine if
fibromyalgia is a discrete construct/ disorder in the clinic.
METHODS: 627 patients seen at an outpatient rheumatology
centre from 1993 to 1996 underwent tender point and
dolorimetry examinations. All completed the assessment scales
for fatigue, sleep disturbance, anxiety, depression, global
severity, pain, functional disability, and a composite
measure of distress constructed from scores of sleep
disturbance, fatigue, anxiety, depression, and global
severity-the rheumatology distress index (RDI).
regression analyses, the RDI was linearly related to the count
of tender points (r2 = 0.30). Lesser associations were found
between the RDI and dolorimetry measurements (r2 = 0.08). The
RDI was more strongly correlated with the two measures of
pain threshold than any of the individual fibromyalgia
symptom variables. In partial correlation analyses, all of
the information relating to symptom variables was contained
in the tender point count, and dolorimetry was not
independently related to symptoms.
CONCLUSION: Tender points
are linearly related to fibromyalgia variables and distress,
and there is no discrete enhancement or perturbation of
fibromyalgia or distress variables associated with very high
levels of tender points. Although fibromyalgia is a
recognisable clinical entity, there seems to be no rationale
for treating fibromyalgia as a discrete disorder, and it
would seem appropriate to consider the entire range of
tenderness and distress in clinic patients as well as in
research studies. The tender point count functions as a
‘sedimentation rate’ for distress, and is a better measure
than the dolorimetry score.