Background Musculoskeletal symptoms in systemic lupus erythematosus (SLE) are common and cause substantial morbidity. However, assessing the nature of these symptoms can be challenging. Multiple recent studies have reported positive musculoskeletal ultrasound (US) findings in SLE patients with joints symptoms. However, the severity of such abnormalities and their relationship to the clinical condition are poorly understood.
Objectives The objectives of this study were to determine the characteristics and severity of musculoskeletal US abnormalities in SLE and to correlate these abnormalities with the clinical condition and BILAG classification.
Methods Patients fulfilling the ACR diagnostic criteria for SLE were included in Leeds and Southampton. Patients had hand US examination (including joints and tendon sheaths) and clinical assessment including BILAG, SLEDAI, tender joint count (TJC) and swollen joint count (SJC). Patients had hematology and immunology assessment. Any patient who had Rhupus (RF or CCP positive) was excluded.
Results A total of 55 patients were recruited. Among them, 18%, 18%, 55% and 9% of patients were BILAG A, B, C and D respectively. In those with inflammatory joint symptoms (BILAG A-C), 58.3% had significant US finding (GS ≥2 and/or PD≥1). All BILAG A had moderate-severe PD (i.e.PD≥2). However, a substantial number of patients who had BILAG B (i.e. clinical synovitis) were judged not to have significant US findings. In contrast, many patients with BILAG C did have significant US abnormality (Table). Erosions were found in about one third of BILAG A patients. Tenosynovitis was also found in a significant number of BILAG A-C patients (Table). 16% of patients had synovitis on US but no swollen joints. There was a moderate positive correlation between presence of PD and presence of erosions (Correlation Coefficient (CC)=0.44 (p<0.001)). There was a strong positive correlation between US synovitis and SJC (CC=0.72 and 0.82 (p<0.001) for GS and PD respectively). However, there was a weak positive correlation between US synovitis and TJC (CC=0.031 and 0.23 (p=0.85 and 0.168) for GS and PD respectively). There was moderate correlation between US synovitis and SLEDAI (CC=0.29 and 0.42 (p=0.002 and 0.033) for GS and PD respectively). Neither inflammatory markers nor SLE immunological markers (i.e ANA, ENA, complements and immunoglobulins)appeared to be associated with joint inflammation.
Conclusions US appears to have value in the assessment and stratification of musculoskeletal symptoms in SLE. Ultrasound was able to detect clinically significant synovitis in patients who had BILAG C or had no swollen joints. In addition, a substantial number of patients with clinical synovitis were judged not to have significant US findings. There was a moderate positive association between PD and joints erosions. Ultrasound may be more sensitive than clinical examination and BILAG in classifying joint pathology in SLE.
Disclosure of Interest None declared