ROME — Clinical articular involvement is strikingly common in patients with systemic sclerosis and is associated with a more active and severe disease phenotype, according to an analysis of the world’s largest systemic sclerosis (SSc) registry.

Synovitis proved to have a particularly strong association with systemic inflammation in this study. However, synovitis often occurred in concert with joint contractures and/or tendon friction rubs, raising the possibility of a shared underlying mechanism in their development, Dr. Jérôme Avouac said at the annual European Congress of Rheumatology.

He presented an analysis of joint symptoms and their clinical implications in 7,286 patients with systemic sclerosis (SSc) enrolled in the EULAR Scleroderma Trials and Research (EUSTAR) registry, the world’s largest SSc database. Of registrants, 58% had the limited cutaneous subtype of SSc, 33% had the diffuse cutaneous subtype, and 9% were not classified.

Active disease, as defined by the 17-point dermal ultrasound, modified Rodnan skin scoring system, was present in 29% of the overall study population. Synovitis was associated with a highly significant 70% increased likelihood of having active disease, while tendon friction rubs were associated with a 51% increased rate. In contrast, joint contractures had no impact upon the risk of having active disease.

Synovitis was also associated with a 47% increased likelihood of having muscle weakness, a 49% increase in the risk of having elevated systolic pulmonary artery pressure, a 49% increase in the odds of having elevation of acute phase reactants, and a 29% increase in anti-topoisomerase-1 antibody positivity.

Patients with joint contractures were significantly more likely to have digital ulcerations (93% increased risk), elevated systolic pulmonary artery pressure (38% increased risk), muscle weakness (41% increase), and pulmonary fibrosis (23% increased risk), the rheumatologist continued.

Tendon friction rubs were associated with a 21% increased likelihood of experiencing digital ulceration, a 22% increase in pulmonary fibrosis, and a 38% greater likelihood of proteinuria.

These study findings provide support for making early detection of articular involvement in SSc a disease-management priority, according to Dr. Avouac.

He noted, however, that this was a cross-sectional analysis. Ongoing prospective follow-up of the EUSTAR registry participants will enable investigators to make a definitive determination of the merits of articular involvement as a predictor of disease severity.

This study was funded by the European League Against Rheumatism. Dr. Avouac declared having no financial conflicts.