title: Pain mechanisms and ultrasonic inflammatory activity as prognostic factors in patients with psoriatic arthritis: protocol for a prospective, exploratory cohort study.
abstract: BACKGROUND
  Persistent pain is a major concern for patients with psoriatic arthritis (PsA). Pain may be due to inflammatory activity or augmented central pain processing. Unawareness of the origin and mechanisms of pain can lead to misinterpretation of disease activity (by composite scores) and erroneous treatments. Ultrasonography (US) is a highly sensitive method to detect tissue inflammation. Evaluating pain mechanisms in relation to US measures may prove valuable in predicting response to treatment in PsA.
  
  
  OBJECTIVE
  To study the association and prognostic value of pain mechanisms, ultrasonic activity and clinical outcomes in patients with PsA who intensify antirheumatic treatment.
  
  
  METHODS
  100 participants >18 years of age with PsA who initiate or switch antirheumatic treatment (biologicals and/or conventional synthetic disease-modifying antirheumatic drugs (DMARDs)) will be prospectively recruited from outpatient clinics in Copenhagen. All data (demographics, clinical, imaging, blood samples and patient-reported outcomes) will be collected at baseline and after 4 months. Pain is assessed by the PainDETECT Questionnaire, Visual Analogue Scale for pain, Swollen to Tender Joint Count Ratio, Widespread Pain Index and tender point examination. The association between pain variables and clinical/US characteristics will be described by correlation analyses. The predictive value of pain measures and baseline US scores on treatment response will be analysed with regression models. Outcomes are composite and clinical, as well as patient reported.
  
  
  BACKGROUND
  The study is approved by the ethics committee of the Capital Region of Denmark (H-15009080) and has been designed in cooperation with patient research partners. The study is registered at clinicaltrials.gov (number NCT02572700). Results will be disseminated through publication in international peer-reviewed journals.
  
  
  BACKGROUND
  NCT02572700, Pre-results.
authors.affiliation: Bispebjerg and Frederiksberg Hospital, The Parker Institute, Frederiksberg, Denmark Department of Rheumatology, Herlev and Gentofte Hospital, Hellerup, Denmark.
authors.forename: Pil
authors.identifier: http://orcid.org/0000-0002-8046-263X
authors.initials: P
authors.lastname: Højgaard
authors.affiliation: Bispebjerg and Frederiksberg Hospital, The Parker Institute, Frederiksberg, Denmark.
authors.forename: Robin
authors.identifier: http://orcid.org/0000-0002-6600-0631
authors.initials: R
authors.lastname: Christensen
authors.affiliation: Bispebjerg and Frederiksberg Hospital, The Parker Institute, Frederiksberg, Denmark Department of Rheumatology, Herlev and Gentofte Hospital, Hellerup, Denmark.
authors.forename: Lene
authors.initials: L
authors.lastname: Dreyer
authors.affiliation: Swedish Medical Center, University of Washington, Seattle, Washington, USA.
authors.forename: Philip
authors.initials: P
authors.lastname: Mease
authors.affiliation: Department of Medical Humanities, VU University Medical Centre, Amsterdam, The Netherlands.
authors.forename: Maarten
authors.initials: M
authors.lastname: de Wit
authors.affiliation: Department of Dermato-Allergology, Herlev and Gentofte Hospital, Hellerup, Denmark Faculty of health and medical sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Lone
authors.initials: L
authors.lastname: Skov
authors.affiliation: Department of Rheumatology, Herlev and Gentofte Hospital, Hellerup, Denmark.
authors.forename: Bente
authors.initials: B
authors.lastname: Glintborg
authors.affiliation: Bispebjerg and Frederiksberg Hospital, The Parker Institute, Frederiksberg, Denmark.
authors.forename: Anton Wulf
authors.initials: AW
authors.lastname: Christensen
authors.affiliation: Bispebjerg and Frederiksberg Hospital, The Parker Institute, Frederiksberg, Denmark.
authors.forename: Christine
authors.initials: C
authors.lastname: Ballegaard
authors.affiliation: Bispebjerg and Frederiksberg Hospital, The Parker Institute, Frederiksberg, Denmark Faculty of health and medical sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Henning
authors.initials: H
authors.lastname: Bliddal
authors.affiliation: Department of Dermato-Allergology, Herlev and Gentofte Hospital, Hellerup, Denmark.
authors.forename: Kristine
authors.initials: K
authors.lastname: Bukhave
authors.affiliation: Bispebjerg and Frederiksberg Hospital, The Parker Institute, Frederiksberg, Denmark.
authors.forename: Else Marie
authors.initials: EM
authors.lastname: Bartels
authors.affiliation: Bispebjerg and Frederiksberg Hospital, The Parker Institute, Frederiksberg, Denmark.
authors.forename: Kirstine
authors.initials: K
authors.lastname: Amris
authors.affiliation: Bispebjerg and Frederiksberg Hospital, The Parker Institute, Frederiksberg, Denmark.
authors.forename: Karen
authors.initials: K
authors.lastname: Ellegaard
authors.affiliation: Bispebjerg and Frederiksberg Hospital, The Parker Institute, Frederiksberg, Denmark.
authors.forename: Lars Erik
authors.initials: LE
authors.lastname: Kristensen
mesh_terms: D018501:Antirheumatic Agents / Q000627:therapeutic use*; D015535:Arthritis, Psoriatic / Q000150:complications / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000503:physiopathology*; D018450:Disease Progression; D005260:Female; D006801:Humans; D007249:Inflammation / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D010146:Pain / Q000188:drug therapy / Q000276:immunology / Q000517:prevention & control*; D010147:Pain Measurement; D011379:Prognosis; D011446:Prospective Studies; D012074:Remission Induction; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: D018501:Antirheumatic Agents
keywords: Psoriatic arthritis; ULTRASONOGRAPHY; outcomes; pain; prognostic factor