Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Can Clinical Phenotype Identify Early Psoriatic Arthritis in an Early Arthritis Cohort?

Coates3,  Laura C., Conaghan3,  Philip G., Emery3,  Paul, Green4,  Michael J., Ibrahim1,  Gamal, MakIver1,  Helen, Helliwell2,  Philip S.

Bradford Hospitals NHS Trust, UK, Bradford, United Kingdom
LIMM, Section of Musculoskeletal Disease, University of Leeds, Leeds, UK
LIMM, Section of Musculoskeletal Disease, University of Leeds, UK
York Hospital NHS Trust, York, UK

Background:

The classification of psoriatic arthritis (CASPAR) criteria are increasingly used to identify psoriatic arthritis. However the initial stem of the CASPAR criteria states that patients must have inflammatory joint, entheseal or spinal disease. The aim of this study was to assess whether the phenotype of inflammatory disease differed between early PsA and other forms of early inflammatory arthritis.

Methods:

Cases of early PsA (less than 24 months symptom duration) and controls with other forms of early inflammatory arthritis who were all disease modifying anti-rheumatic drug naive were recruited. Gold standard diagnosis was confirmed by a consultant rheumatologist. A 66/68 joint count, enthesitis count (Maastricht Ankylosing Spondylitis Enthesitis Score – MASES, Leeds Enthesitis Index – LEI and plantar fascia) and assessment of axial disease were performed to assess presence of inflammatory disease.

Results:

111 early PsA cases and 111 early arthritis controls (RA n=82, undifferentiated arthritis n=13, spondyloarthritis n=9, inflamm OA n=4, crystal arthritis n=3) were recruited. All but one of the controls had arthritis. The pattern of arthritis (oligoarticular vs polyarticular) and the average tender and swollen joint counts did not differ significantly between cases and controls. DIP joint involvement was significantly more common in PsA cases than controls (32% vs 16%, p=0.007). When comparing PsA cases only to controls with RA (n=82), PsA cases had significantly lower joint counts (p<0.008)

Presence of enthesitis was significantly more frequent in the PsA patients compared to controls (67% vs 52%, p=0.029). There was a trend towards higher enthesitis counts in PsA cases compared to control patients but this was not significant. Spondylitis appeared more frequent in the PsA patients but the difference was not significant due to small numbers (5% vs 1%, p=0.055).

 Cases (n=111)Controls (n=111)RA controls (n=82)
Proportion with arthritis (%)10099100
Oligoarthritis (%)302415
Polyarthritis (%)707685
DIP joint involvement (%)321618
Median TJC (IQ range)7 (13)8 (15)12 (16)
Median SJC (IQ range)5 (7)5 (9)7 (11)
Proportion with enthesitis (%)675252
Median enthesitis count (IQ range)2 (4)1 (3)1 (4)
Proportion with spondylitis (%)510

Conclusion:

Different clinical phenotype cannot be relied upon to identify early psoriatic arthritis. Enthesitis and DIP joint involvement are more frequent in early PsA compared to other forms of inflammatory arthritis, however a significant proportion of controls (including a significant proportion of patients with RA) also have clinical enthesitis. Spondylitis is likely to be more frequent in PsA than in RA, however it cannot be relied upon to differentiate from other forms of inflammatory arthritis.

To cite this abstract, please use the following information:
Coates, Laura C., Conaghan, Philip G., Emery, Paul, Green, Michael J., Ibrahim, Gamal, MakIver, Helen, et al; Can Clinical Phenotype Identify Early Psoriatic Arthritis in an Early Arthritis Cohort? [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1926
DOI: 10.1002/art.29691

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