title: Non-nociceptive pain in rheumatoid arthritis is frequent and affects disease activity estimation: cross-sectional data from the FRAME study.
abstract: BACKGROUND
  The painDETECT questionnaire (PDQ) is a mechanism-based pain classification tool assigning patients to one of three categories depending on the quality of the experienced pain. Patients with non-nociceptive pain score high on the PDQ. The objective was to assess the proportions of the three PDQ classification groups in patients with rheumatoid arthritis (RA) and to explore differences in clinical characteristics.
  
  
  METHODS
  RA patients initiating or escalating their RA therapy were included prospectively and underwent a thorough examination programme. Low (PDQ score < 13), medium (PDQ score 13-18), and high (PDQ score > 18) scores indicate nociceptive, unclear/possible neuropathic, or neuropathic pain mechanisms, respectively.
  
  
  RESULTS
  The 102 included patients were classified into the following PDQ classification groups: low = 65%, medium = 23%, and high = 12%. Patients in the medium and high PDQ groups scored worse on indicators of anxiety, depression, disability, mental health-related quality of life, pain, and fatigue. They also had more tender points and an RA disease activity score based on 28 joints (DAS28) where a higher fraction of the composite score pertained to non-inflammatory factors compared to patients in the low PDQ classification group. There were no differences in objective inflammatory indices across groups. Multiple regression analysis demonstrated that the tender joint count (TJC) and the 36-item Short Form Health Survey (SF36) mental component summary (MCS) score were independently associated with the PDQ score.
  
  
  CONCLUSIONS
  In patients initiating or intensifying medical treatment for their RA, non-nociceptive pain (PDQ score ≥ 13) is common. In these patients, the pain mechanisms result in increased disease activity scores on a non-inflammatory basis.
authors.affiliation: a The Parker Institute, Department of Rheumatology , Copenhagen University Hospital , Bispebjerg and Frederiksberg, Frederiksberg , Denmark.
authors.forename: A W
authors.initials: AW
authors.lastname: Christensen
authors.affiliation: a The Parker Institute, Department of Rheumatology , Copenhagen University Hospital , Bispebjerg and Frederiksberg, Frederiksberg , Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Rifbjerg-Madsen
authors.affiliation: a The Parker Institute, Department of Rheumatology , Copenhagen University Hospital , Bispebjerg and Frederiksberg, Frederiksberg , Denmark.
authors.forename: R
authors.initials: R
authors.lastname: Christensen
authors.affiliation: b Department of Rheumatology , Copenhagen University Hospital , Herlev and Gentofte, Gentofte , Denmark.
authors.forename: L
authors.initials: L
authors.lastname: Dreyer
authors.affiliation: b Department of Rheumatology , Copenhagen University Hospital , Herlev and Gentofte, Gentofte , Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Tillingsøe
authors.affiliation: c Department of Rheumatology , Copenhagen University Hospital , Køge , Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Seven
authors.affiliation: a The Parker Institute, Department of Rheumatology , Copenhagen University Hospital , Bispebjerg and Frederiksberg, Frederiksberg , Denmark.|d Department of Radiology , Copenhagen University Hospital , Bispebjerg and Frederiksberg, Frederiksberg , Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Boesen
authors.affiliation: a The Parker Institute, Department of Rheumatology , Copenhagen University Hospital , Bispebjerg and Frederiksberg, Frederiksberg , Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Ellegaard
authors.affiliation: a The Parker Institute, Department of Rheumatology , Copenhagen University Hospital , Bispebjerg and Frederiksberg, Frederiksberg , Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Bliddal
authors.affiliation: a The Parker Institute, Department of Rheumatology , Copenhagen University Hospital , Bispebjerg and Frederiksberg, Frederiksberg , Denmark.
authors.forename: B
authors.initials: B
authors.lastname: Danneskiold-Samsøe
authors.affiliation: a The Parker Institute, Department of Rheumatology , Copenhagen University Hospital , Bispebjerg and Frederiksberg, Frederiksberg , Denmark.
authors.forename: K
authors.initials: K
authors.lastname: Amris
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D059225:Nociception; D010146:Pain / Q000145:classification*; D010147:Pain Measurement; D012044:Regression Analysis; D012720:Severity of Illness Index