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C l AS sification criteria for the diagnosis of P soriatic AR thritis: The CASPAR Study

Wellington Regional Rheumatology Unit, Hutt Hospital, Wellington, New Zealand. C l AS sification criteria for the diagnosis of P soriatic AR thritis: The CASPAR Study. Taylor W 4 , Helliwell P 1 , Gladman D 3 , Mease P 5 , Mielants H 6 , Marchesoni A 2 , for the CASPAR investigators .

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C l AS sification criteria for the diagnosis of P soriatic AR thritis: The CASPAR Study

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  1. Wellington Regional Rheumatology Unit, Hutt Hospital, Wellington, New Zealand ClASsification criteria for the diagnosis of Psoriatic ARthritis: The CASPAR Study Taylor W4, Helliwell P1, Gladman D3, Mease P5, Mielants H6, Marchesoni A2, for the CASPAR investigators. 1Academic Unit of Musculoskeletal Medicine, University of Leeds, UK; 2Istitutio Ortopedico G. Pini, Milan, Italy; 3University of Toronto, Canada; 4University of Otago, Wellington, New Zealand; 5Seattle Rheumatology Associates, USA; 6University of Ghent, Belgium. Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  2. Australia: M Lassere; Belgium: H Mielants, M Van de Berghe, H Zmierczak, K de Vlam; Canada: A Russell, D Gladman; France: B Fournie, M Dougados, E Dernis, L Gossec, D Zerkak; Ireland: D Veale, O Fitzgerald, M O’Rouke; Morocco: N Hajjaj-Hassouni, N Bentalha; New Zealand: W Taylor, P Healy; Italy: A Marchesoni, C Salvarani, P Macchioni, E Lubrano, I Olivieri; South Africa: A Kalla, J Potts, G Mody, N Patel; Spain: J Torre Alonso; Sweden: B Svensson, U Lindqvist, G Holmstrom, E Theander, S Dahlqvist, G Alenius, K Ek; United Kingdom: A Isdale, D McGonagle, J Holdsworth, H Sharlala, A Adebajo, L Kay, N McHugh, J Lewis, P Owen, N Barkham, V Bejarano, P Emery, P Helliwell, G Ibrahim; United States: C Ritchlin, L Espinoza, L Candia, P Mease, L Wang, L Gunter. The CASPAR investigators Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  3. Background • Classification criteria for distinguishing between groups of PsA and non-PsA • There are 7 proposed classification criteria for the diagnosis of PsA • Only 1 has been derived from observed data • None have been adequately validated Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  4. Moll & Wright (1973) • Bennett (1979) • Vasey & Espinoza (1984) • Gladman (1987) • ESSG (1991) • McGonagle (1999) • Fournie (1999) Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  5. Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  6. Background • There are 7 proposed classification criteria for the diagnosis of PsA • Only 1 has been derived from observed data • None have been adequately validated • In 2001, CASPAR arose from a collaborative effort determined to address this problem Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  7. Aim • To compare the test performance characteristics of existing classification criteria • To determine whether new criteria derived from observed data would be more accurate than existing criteria Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  8. Design • Prospective, observational study of consecutive clinic patients with PsA and other inflammatory arthritis • Target sample size of 1012 in total • 30 clinics in 13 countries • Gold-standard of diagnosis based on physician’s opinion • Data collected between Feb 02 to Mar 04 Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  9. Methods • Data collected included: • Clinical and examination features • Xrays of spine, sacroiliac joints, hands and feet • Rheumatoid factor, [HLA], anti-CCP, stored blood • Xrays were read centrally by 2 readers in tandem, blinded to diagnosis • Clinical gold-standard validated by quality control and Latent Class Analysis (statistical modelling) • New criteria developed using CART and logistic regression Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  10. Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  11. Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  12. Worse specificity Better specificity Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  13. Worse specificity Better specificity Better sensitivity Worse sensitivity Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  14. Validation of ‘gold-standard’ • Data control committee closely examined the data for 124 randomly selected subjects (only 1 control reclassified as PsA) • Latent Class Anlaysis used to reclassify subjects on the basis of modelling using the agreement pattern between existing criteria: very close agreement with clinical diagnosis (kappa >0.9) Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  15. Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  16. Vasey & EspinozaIn: Calin A, editor. Spondyloarthropathies. Orlando, Florida: Grune & Stratton; 1984. p. 151-185 Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  17. CART analysis • Iterative partitioning of the dataset using most discriminating variables to produce the most ‘pure’ groups; progressive pruning back of the tree to balance complexity with accuracy • CART selected only 2 variables: • history of psoriasis and current psoriasis • surrogates: nail dystrophy, family history, dactylitis, RF • specificity 96.8%; sensitivity 96.1% Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  18. Discrimination of clinical, laboratory and xray items Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  19. Current psoriasis • History of psoriasis (if current psoriasis not present) • Family history of psoriasis (if neither history nor current psoriasis is present) • Psoriatic nail dystrophy • RF negative • Current dactylitis • History of dactylitis (if current dactylitis not present) • Xray signs of juxta-articular new bone formation (3 or more items) Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  20. CASPAR criteria Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  21. Conclusion • Robust design (large sample, many centres, unselected subjects, validation of gold-standard, large number of items examined, convergence of separate statistical approaches) • Results not applicable to early disease or to non-rheumatic populations (e.g. general population) • CASPAR criteria are simple, highly specific, and derived from observed patient data: a new standard for the case-definition of PsA? Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  22. Acknowledgements Funding:EULAR, Barnsley District NHS Trust, Groote Schuur Hospital (Cape Town), Department of Medical Sciences (University Hospital, Uppsala), Krembil Foundation, St. Vincent’s University Hospital Radiology Department (Dublin), Inkosi Albert Luthuli Central Hospital (Durban), El Ayachi Hospital (Morocco), National Psoriasis Foundation (USA), The Foundation for Scientific Research of the Belgian Society of Rhumatology, Arthritis New Zealand. Data Quality Committee: Dennis McGonagle, Philip Helliwell, Mike Green, Leeds; Deborah Symmons, Manchester, UK Radiology: Guy Porter, Keighly, UK CCP analysis: Neil McHugh, Pat Owen, Bath, UK Statistical analysis:John Horwood, Christchurch, NZ Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  23. Discussion • Is better specificity worth the trade-off with sensitivity? • Construction of CASPAR criteria • Dependent nature of some items • Meaning of the initial mandatory criterion (note that 1.6% of dataset had no involved joints)? • Should some degree of chronicity be required? • Practical application of CASPAR criteria • Should dactylitis be excluded from the initial mandatory criterion (“double-dipping”)? • Hands and feet xrays required Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  24. Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  25. Anti-CCP performance Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

  26. Rehabilitation Teaching & Research Unit, Wellington School of Medicine & Health Sciences, University of Otago

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