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GRAPPA-OMERACT initiative to standardise outcomes in psoriatic arthritis clinical trials and longitudinal observational studies
  1. William Tillett1,2,
  2. Ana-Maria Orbai3,
  3. Alexis Ogdie4,
  4. Ying Ying Leung5,
  5. Vibeke Strand6,
  6. Dafna D Gladman7,
  7. Philip J Mease8,
  8. Laura C Coates9
  9. On Behalf of the GRAPPA OMERACT Psoriatic Arthritis working group
  1. 1 Royal National Hospital for Rheumatic Disease, Bath, UK
  2. 2 Pharmacy and Pharmacology, University of Bath, Bath, UK
  3. 3 Department of Medicine/Rheumatology, Johns Hopkins University, Baltimore, Maryland, USA
  4. 4 Division of Rheumatology and Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
  5. 5 Department of Rheumatology and Immunology, Singapore General Hospital, Singapore, Singapore
  6. 6 Department of Immunology/Rheumatology, Stanford University, Stanford, California, USA
  7. 7 Krembil Research Institute, University Health Network,Toronto Western Hospital, Toronto, Ontario, Canada
  8. 8 Department of Rheumatology Research, Swedish Medical Center, Seattle, Washington, USA
  9. 9 Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, UK
  1. Correspondence to Dr William Tillett, Royal National Hospital for Rheumatic Disease, University of Bath, BA11RL, Bath, UK; w.tillett{at}

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We read with interest the recent letter by Ramiro et al 1 reporting data from a systematic literature review on the measurement of enthesitis, dactylitis and nail disease in psoriatic arthritis (PsA) clinical trials. The authors highlight the great variety in the outcome measures chosen, cut points and the statistical analysis performed (percentage change, proportion resolved). We are pleased the authors have highlighted this problem and agree with their viewpoints on the clear lack of standardisation of domains and instruments in clinical trials evidenced by the data. Indeed this inconsistency of data reporting has led to significant heterogeneity in both physician-assessed and patient-reported outcomes particularly in the field of PsA. It is the domains of enthesitis, dactylitis, …

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  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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