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.


Agreement between Total Joint Count and DAS 28 Joint Count in Psoriatic Arthritis.

Fernandez-Sueiro1,  Jose Luis, de Rabago1,  Eugenia Gonzalez Diaz, Pinto-Tasende1,  J., Pertega-Diaz1,  Sonia, Fernandez-Lopez1,  J. C., Oreiro-Villar1,  N., Galdo1,  F.

Complejo Hospitalario Universitario La Coruña, La Coruña, Spain
Complejo Hospitalario Universitario La Coruña, A Coruna, Spain

Background:

Distal interphalangeal involvement is a characteristic feature of psoriatic arthritis (PsA), in this sense total joint count in PsA can be considered as 78 tender and 76 swollen joints. DAS 28 only evaluates 28 joints, therefore it is not clear whether counting only 28 joints is sufficient to evaluate peripheral joint involvement in PsA.

Objective:

to evaluate the agreement between total joint count and DAS 28 joint count in PsA patients.

Patients and Methods:

analysis at three consecutive time points (T0, T1 and T2) of a longitudinal observational cohort of PsA patients. In all patients total joint count (78 tender joint count (TJC) and 76 swollen joint count (SJC)) were performed. Analysis of the agreement between total joint count and DAS28 joint count was performed with the Bland-Altman methodology and the Kappa index.

Results:

Mean TJC was: T0 total 3.9±6.7 vs DAS28: 2.5±5.0 (p<0,001), T1 2.3±4.5 vs 1.2±2.7 (p<0.001), T2 3.2±7.3 vs 1.8±4.5 (p=0.001). Mean SJC: T0 total 1.3±3.5 versus DAS28 0.9±2.7 (p=0.004), T1 0.6±0.5 vs 0.5±1.5 (p=0.002), T2 0.5±1.5 vs 0.1±0.4 (p=0.021). The mean difference between the number of tender joints (total joint count – DAS 28) was: T0 1.4±3.0, T1 1.3±2.9, T2 1.4±3.7, in swollen joints was T0 0.4±1.7, T1 0.3±1.1, T2 0.3±1.5.

Disagreement in one or more tender joints between the total count and the DAS 28 was found in T0 30.4%, T1 28.8%, T2 28.3% of the patients. In swollen joints, these figures were T0 11.1%, T1 14.4% and T2 13.0%. After categorizing TJC in <=1 joint and >1 joint, Kappa index for the agreement between the total joint count and DAS28 was T0 0.764, T1 0.722, T2 0.836. For SJC, Kappa index was T0 0.811, T1 0.704, T2 0.378.

Using DAS28 joint count, at T0 51.9% (T1 60.5%, T2 65.5%) of the patients met minimal disease activity criteria. Of these, 7.5% (T1 12.0%, T2 5.1%) would not meet the criteria when using the total joint count (Kappa index=0.923).

Conclusions:

At three different time-points, there are differences between total tender and swollen joint count and DAS 28 joint count, however the agreement between total joint count and DAS28 is high. On the other hand the agreement to classify patients with minimal disease activity is fairly good. These data suggest that DAS 28 joint count may be reliable for evaluating peripheral involvement in PsA.

To cite this abstract, please use the following information:
Fernandez-Sueiro, Jose Luis, de Rabago, Eugenia Gonzalez Diaz, Pinto-Tasende, J., Pertega-Diaz, Sonia, Fernandez-Lopez, J. C., Oreiro-Villar, N., et al; Agreement between Total Joint Count and DAS 28 Joint Count in Psoriatic Arthritis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1920
DOI: 10.1002/art.29685

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