Systemic lupus erythematosus (SLE) and primary Sjögren's syndrome (SS) can be associated with inflammatory arthritis, which is underdiagnosed by clinical examination. The aim of this cross-sectional, observational study was to compare, for the first time, the ultrasound (US)-detected joint abnormalities in these two diseases and to define the role of US in patient management. Participants had SLE (n = 18) and SS (n = 23), symptoms of hand joint pain and no previous diagnosis of arthritis. Data on disease activity, duration, damage scores, inflammatory and serologic markers, treatment and clinical and ultrasound parameters (derived from the assessment of 902 joints) were analysed and correlated using descriptive statistics, correlation tests and regression models. Subclinical synovitis/tenosynovitis was detected in 44.4% of SLE patients and 21.7% of SS patients (p = 0.23). There was no significant correlation between either the total Power Doppler score or the total grey-scale score and disease activity scores (British Isles Lupus Assessment Group index and European League Against Rheumatism Sjögren's syndrome disease activity index). Both damage scores (Systemic Lupus International Collaborating Clinics index and Sjögren's syndrome disease damage index) correlated with the total grey-scale synovitis score. Significant proportions of the participants with SLE and SS had erosions (55.6% and 34.8%, respectively, p = 0.184) and osteophytes (61.1% vs. 60.9%, p = 0.98) in at least one joint. The lack of correlation between disease activity scores and US outcome measures indicated their limitations in diagnosing subclinical synovitis in SLE and SS patients. Future research is needed to determine if the development of erosions could be prevented by early diagnosis and prompt treatment of inflammatory arthritis associated with SLE and SS.
Keywords: Arthritis; Power Doppler signal; Sjögren's syndrome; Systemic lupus erythematosus; Ultrasound; erosions.
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