Psoriatic arthritis definition and classification criteria
Philip Helliwell Senior Lecturer in Rheumatology University of
Leeds
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Psoriatic arthritis Wright V Annals of Rheumatic Diseases
1961;20:123-132
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Too sensitive? Too specific?
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Psoriatic arthritis key individual features Psoriasis Symmetry
Rheumatoid factor
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Psoriasis May be hidden May be coming May have gone May be in
family May be misdiagnosed
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Symmetry in early and late psoriatic and rheumatoid
arthritis
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Joint frequency by disease
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Psoriatic arthritis - the significance of rheumatoid factor
Moll and Wright excluded (usually) Gladman (and others) included (
up to 15%) Not unreasonable to allow RF as may just reflect a
chronic inflammatory state Need to: Reliably exclude the
seronegative rheumatoid arthritis Reliably include the seropositive
psoriatic arthritis
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Rheumatoid factor Could we make this test more specific?
Rheumatoid factor isotypes Or use other tests? Anti-perinuclear
factor Anti-CCP antibodies
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Summary of CART analysis Variables entered Splitters selected
by CART SensSpec All dataCurrent psoriasis0.980.99 All data
excluding psoriasis RF, dactylitis0.970.78 All except psoriasis and
RF Dactylitis, nodules, symmetry, chest wall pain, juxta-articular
new bone, 4 mcp joints, sacroiliitis, PVO, ankylosis, entheseal new
bone, chest wall pain, clinical spondylitis 0.890.73
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Psoriatic arthritis one disease or more? Large joint
mono/oligoarthritis Entheseal disease (including spinal disease)
SAPHO/CRMO DiP and mutilans Symmetrical polyarthritis + Ps =
RA?
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Psoriatic arthritis does it exist? Cats believed psoriasis
merely modifies inflammatory response Immunogenetic data not all
that convincing Inflammatory response has an array of common
pathways
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Psoriatic arthritis why bother? Same NSAIDs Same DMARDs Same
biologics BUT Nosology Good and bad prognostic disease Treatment
outcome Treatment indications
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Impairment, disability and quality of life in RA and PsA
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Disability and quality of life in RA and psoriatic arthritis
according to severity of arthritis
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Validation of classification criteria for psoriatic arthritis
700 patients with psoriatic arthritis 700 controls with
inflammatory arthritis and inflammatory OA Standardised proforma
Clinical and historic data Radiographic data Genetic data Quality
control A prospective multi-centre international case control
study
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Analysis by: Conditional logistic regression Latent class
analysis Classification and regression trees International study
All major players Consensus criteria Based on sound methodology
Validation of classification criteria for psoriatic arthritis
RESULTS AVAILABLE IN 2003 2004
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What will CASPAR do? Enable us all to use the same criteria
Distinguish between seronegative rheumatoid arthritis and psoriatic
arthritis Facilitate studies of natural history Treatment
immunogenetics
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Psoriatic arthritis Is a distinctive disorder New criteria need
to encapsulate this while not being exclusive A distinctive (and
preferably pathogenic) biologic marker would help