Background Musculoskeletal ultrasound (US) has been shown to be a sensitive tool to detect inflammation in inflammatory arthritides . In practice, the composite clinical metric DAS28 is used as a feasible tool for measurement of disease activity, not only in rheumatoid arthritis but also for peripheral arthritis in psoriatic arthritis (PsA). Although both types of measures may reflect disease activity in inflammatory arthritis, some data have shown a poor correlation between clinical and US findings .
Objectives To compare clinical and US assessments of active disease in PsA patients.
Methods In this cross sectional study PsA patients were consecutively recruited from an outpatient clinic. All the patients fulfilled the CASPAR criteria for PsA. The patients underwent a US examination of 34 joints. In addition, joints found to be swollen or tender by 66/68 joint count (SJC/TJC) were assessed. The US examinations were performed by an experienced rheumatologist (AD) and the SJC and TCJ used for DAS28 calculation were performed by special trained nurses. Presence of US arthritis was defined by gray scale score ≥2 and/or power Doppler ≥1 (0-3 scale for both).
Results A total of 133 PsA patients were recruited. Mean (SD) age was 52.1 (10.3) years, mean disease duration 10 (6.7) years and 53% were females. 32 (24.1%) patients were found to be both in clinical (DAS28<2.6) and US remission; 12 (9.8%) patients were found to have active disease on US despite being in clinical remission; 50 (37.6%) patients were found to be in US remission but not in clinical remission (Table). No significant correlation was found between DAS28 score and the presence of inflammation on US (rho=0.079, p=0.37). A significant correlation between US and clinical findings was only found for 66 SJC (rho=0.22, p=0.01) and assessors global health (rho=0.202, p=0.02); there was no correlation between US evaluation and 68 TCJ, SR, CRP or patient global health.
Conclusions These data reveal poor correlation between DAS28 and the presence of arthritis on US. A weak correlation between US and clinical findings was only found for SJC and physician global health. The discrepancy between US and clinical findings may indicate that patient disease perception may not only be explained by inflammatory mechanisms but also by other mechanisms.
Brown A.K. et al, Presence of Significant Synovitis in Rheumatoid Arthritis Patients With Disease-Modifying Antirheumatic Drug –Induced Clinical Remission, Arthritis and Rheumatism, vol.54, No.12, Dec 2006, pp 3761-3773.
Husic R et al, Disparity between ultrasound and clinical findings in psoriatic arthritis, Ann Rheum Dis -2012-203073.
Disclosure of Interest B. Michelsen: None declared, A. Diamantopoulos: None declared, A. Kavanaugh: None declared, G. Haugeberg Grant/research support: Unrestricted grant from Pfizer
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