title: A cluster within the continuum of biopsychosocial distress can be labeled "fibromyalgia syndrome"--evidence from a representative German population survey.
abstract: OBJECTIVE
  We tested the hypothesis that "fibromyalgia syndrome" is a biopsychosocial continuum disorder.
  
  
  METHODS
  A cross-sectional survey of a representative sample of the German general population with persons >or= 14 years of age was conducted based on face-to-face contacts. Physical distress was measured by the regional pain scale (RPS) and the Patient Health Questionnaire 15 (PHQ-15), psychological distress by the PHQ-9, and social distress by the Oslo Social Support Scale. Health-related quality of life (HRQOL) was measured by the 12-item form of the Medical Outcome Study Short Form Health Survey. A k-means clustering procedure with 2-8 clusters preset was used to classify the scores of the RPS, PHQ-9, and PHQ-15. The number of clusters retained was based on the stability and interpretability of the clusters. The cluster analysis was first performed with a randomly selected half of the sample and then cross-validated on the second half of the total sample.
  
  
  RESULTS
  A 4-cluster solution produced the most stable and meaningful results. Cluster 1 was very low on all symptom scores. Cluster 2 was low on pain sites, somatic symptoms, and depression. Cluster 3 was high on pain scores, moderate on somatic symptoms, and low on depression. Cluster 4 was high on all symptom scores. The centroids of cluster 4 met the survey criteria of fibromyalgia syndrome. Cluster 4 reported a lower HRQOL and less social support compared to the other 3 groups.
  
  
  CONCLUSIONS
  A cluster within the continuum of biopsychosocial distress can be labeled fibromyalgia syndrome.
authors.affiliation: Department of Internal Medicine I, Klinikum Saarbrücken, Saarbrücken, Germany. whaeuser@klinikum-saarbruecken.de
authors.forename: Winfried
authors.initials: W
authors.lastname: Häuser
authors.forename: Gabriele
authors.initials: G
authors.lastname: Schmutzer
authors.forename: Elmar
authors.initials: E
authors.lastname: Brähler
authors.forename: Heide
authors.initials: H
authors.lastname: Glaesmer
mesh_terms: D000328:Adult; D016000:Cluster Analysis; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D005356:Fibromyalgia / Q000145:classification / Q000503:physiopathology / Q000523:psychology*; D005858:Germany; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D011569:Psychiatric Status Rating Scales; D011584:Psychology; D011788:Quality of Life; D013315:Stress, Psychological; D011795:Surveys and Questionnaires; D055815:Young Adult