Objective. To determine the risk of a diagnosis of osteoarthritis (OA) in patients with psoriatic arthritis (PsA) compared to patients with psoriasis and a general population cohort. Methods. Incident PsA patients aged 18-89 years at diagnosis were identified from the United Kingdom Clinical Practice Research Datalink between 1998 and 2014. All patients with PsA were matched to 2 cohorts of patients, both at a 1:4 ratio. The first cohort included patients with psoriasis (and no PsA) and the second was a general population cohort (with no psoriasis or PsA). The baseline prevalence of OA was calculated for each study cohort. The incidence of OA was calculated, and adjusted relative risks (RRadj) were calculated using conditional Poisson regression. Results. We identified 6783 incident PsA patients. The baseline prevalence of OA ranged from 22.1% (95% CI 21.1-23.1) in the PsA cohort to 12.6% (95% CI 12.2-13.0) and 11.0% (95% CI 10.6-11.3) in the psoriasis and general population cohorts, respectively. The incidence of OA was significantly higher in the PsA cohort compared to the psoriasis and general population cohorts after adjusting for BMI (RRadj 1.68, 95% CI 1.46-1.93, and RRadj 1.86, 95% CI 1.62-2.14, respectively). Conclusion. An increased risk of OA was observed in patients with PsA compared to patients with psoriasis alone and those in the general population. Further work is needed to determine whether this reflects a true increase in OA risk or misdiagnosed PsA, and the extent to which it can be explained by differences in the opportunity for OA diagnosis between cohorts.

Original languageEnglish
Pages (from-to)841-846
Number of pages6
JournalThe Journal of Rheumatology
Issue number6
Early online date15 Nov 2020
Publication statusPublished - 1 Jun 2021

Bibliographical note

Funding Information:
This report is independent research funded by the National Institute for Health Research (NIHR), Programme Grants for Applied Research (Early detection to improve outcome in patients with undiagnosed PsA [PROMPT], RP-PG-1212-20007). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. 1R.A. Charlton, Research Fellow, PhD, A. Green, Research Officer, MSc, J. Snowball, Research Fellow, MSc, A. Nightingale, Research Fellow, PhD, N.J. McHugh, Professor of Pharmacoepidemiology, MBChB, MD, Department of Pharmacy and Pharmacology, University of Bath, Bath; 2G. Shaddick, Professor of Statistics, PhD, Department of Mathematics, University of Exeter; 3W. Tillett, Consultant Rheumatologist and Senior Lecturer, MBChB, PhD, Department of Pharmacy and Pharmacology, University of Bath, Bath, and Royal National Hospital for Rheumatic Diseases, Bath; 4C. Smith, Professor of Dermatology and Therapeutics, MD, FRCP, Guys and St Thomas’ NHS Foundation Trust, London, UK. All authors report grants from the NIHR (RP-PG-1212-20007) during the conduct of the study. CS reports grants from the Medical Research Council (MR/L011808/1) outside the submitted work. Address correspondence to Prof. N.J. McHugh, Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath, BA2 7AY, UK. Email: [email protected]. Accepted for publication November 4, 2020.

Publisher Copyright:
Copyright © 2021. All rights reserved.


  • Cohort study
  • Osteoarthritis
  • Psoriasis
  • Psoriatic arthritis

ASJC Scopus subject areas

  • Immunology and Allergy
  • Rheumatology
  • Immunology


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