Ultrasound-Based Detection Of Subclinical Arthritis Among Patients With Systemic Lupus

Systemic Lupus Erythematosus (SLE) is a chronic inflammatory autoimmune disorder associated with a wide range of symptoms and physical findings. It is characterized by loss of tolerance to self-antigens, formation of immune complexes, and an activated type I interferon system . Joint involvement is one of the most common features of systemic lupus erythematosus (SLE), with up to 95% of patients experiencing arthralgia or arthritis during the course of their disease . While multiple joints can be affected, nearly 50% of patients report difficulties in daily life performance due to hand symptoms . Traditionally, SLE arthritis is considered to be mild, reversible and non-erosive, with only 5-15% of cases progressing to deforming arthropathy, either erosive-as in rhupus syndrome (an overlap of SLE with rheumatoid arthritis (RA))-or non-erosive-as in Jaccoud's arthropathy . In routine clinical practice, joint involvement is usually assessed with physical examination and radiographical studies. However, this approach has been shown to have a low sensitivity for joint abnormalities when compared with ultrasound (US) evaluation or MRI, suggesting that the burden of joint inflammation may be underestimated in the current clinical practice . The value of US with power Doppler (PD) in inflammatory arthritis has been extensively demonstrated in the literature, with similar sensitivity and specificity in the detection of synovitis in comparison with MRI, with the advantage of being more accessible and less expensive . While US shows the morphology of the synovial membrane, PD identifies increased vascularisation within it, allowing for the detection of active joint inflammation. It is known that in RA synovial abnormalities are present before clinically evident arthritis develops, and that early treatment can limit erosive changes and avoid disease progression. In this context, US PD has nowadays an established role in the detection of subclinical joint inflammation in RA, namely to predict progression in patients with clinical remission . Although there is evidence that US PD is a valuable technique in the evaluation of musculoskeletal symptoms in SLE, the prevalence of subclinical joint abnormalities in SLE remains to be defined. Furthermore, while it is known that minimal synovial proliferation may be seen in up to 50% of healthy subjects, the distinction between 'normal' synovial hypertrophy (SH) and pathological subclinical synovitis in SLE still requires clarification .