Background Musculoskeletal symptoms are common in systemic lupus erythematosus (SLE) and are associated with significant morbidity. However, assessing their nature can be challenging, with implications for treatment decisions and measuring response. Ultrasound (US) has been shown to be valid and reliable for the assessment of other inflammatory arthritides but data in SLE are more limited.
Objectives The objectives of this systematic literature review were to determine the characteristics of musculoskeletal US abnormalities in SLE and to evaluate its metric properties in the detection and quantification of musculoskeletal symptoms.
Methods We systematically searched the literature using the PubMed, Embase and Cochrane Library databases for studies used musculoskeletal US for assessing SLE from 1st of January 1950 to 1st of August 2014. Studies were assessed for quality using Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool and for their metric qualities including reliability and validity.
Results The search yielded 1165 citations, after the review process nine studies were included in the final analysis. A total of 459 SLE patients were recruited in these studies. Sample sizes ranged from 17-108 patients. There was heterogeneity in the populations studied as only two studies clearly separated the rhupus group and the non-rhupus SLE group. The overall quality of the studies included showed moderate to high risk of bias and applicability concerns as assessed using the QUADAS-2 instrument. Most studies either did not clarify whether rhupus patients were separated in the analysis or did not report rheumatoid factor (RF), which could have affected US findings. Most studies did not specify the window of period permitted for use of concomitant non-steroidal anti-inflammatory drugs (NSAIDS) and oral prednisolone prior to US examination. None of the included studies assessed criterion validity by comparison to a gold standard. Most studies have used the OMERACT definition of synovitis but reported binary findings (synovitis/no synovitis) or might have given mean US score for synovitis without specifying grey scale (GS) or power Doppler (PD) and/or rates of different scores. All nine studies used grade 1 GS with or without PD to define synovitis. Overall, synovitis and tenosynovitis were reported in 25-94% and 28-65% of patients respectively; PD and erosions were reported in 10-82% and 2-41% of patients respectively. There was poor to moderate association between US abnormalities and disease activity indices and immunological findings. In terms of discriminant validity, five studies (56%) reported inter and/or intra-reader reliability. The range of intra-reader reliability was between 0.78-1.00 while the inter-reader reliability ranged between 0.68-0.96.
Conclusions US has potential value in the assessment of musculoskeletal symptoms in SLE. However, there is methodological variation between studies that may account for lack of consensus on US abnormalities. Studies that address these problems are required before US can used as an outcome measure in SLE.
Disclosure of Interest None declared