CAN WE IDENTIFY A ”PURE” FIBROMYALGIA (FM) PHENOTYPE?
Background and aims: There is ongoing controversy about the diagnosis of FM. Several protocols based on signs and symptoms have been proposed without any common agreement. This makes research difficult since patient groups in reported studies are not homogeneous. The aim if this study was to use signs and symptoms from several protocols to identify cut points to separate a “pure” FM phenotype from “fibromyalgianess” in a large sample from a general population. 
Methods: As part of the HUNT pain examination study, 551 individuals from a general population in mid-Norway were interviewed and examined by a team of a physiotherapist and a pain physician.  Tender point examinations were conducted on all subjects as per the ACR 1990 guidelines but using a 0 – 10 VRS scale for pain at each point. Sleep (ISI), fatigue (CFS) and mental health (SF-8) were also assessed. An attempt was made to identify cut points for pain VRS, sleep, fatigue and mental health that could be correlated to identify a “pure” fibromyalgia phenotype suitable for use in research.
Results: No clear cut points could be identified. The data all supported the literature in that the signs and symptoms of FM used for both clinical and research diagnosis indicate a continuum of increasing severity.
Conclusions: The syndrome of FM represents a uniform severity continuum of signs and symptoms and the ability to identify what is and is not “true” fibromyalgia continues to be a problem for both research and the clinic.

CAN WE IDENTIFY A "PURE" FIBROMYALGIA (FM) PHENOTYPE?