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Researchers found no association between anti-U1RNP autoantibodies and 3-year ILD progression or mortality in patients with systemic sclerosis-associated ILD.

Updated results of a study by Gonçalo Boleto, MD, and colleagues were published in abstract form in Annals of the Rheumatic Diseases. The researchers leveraged the European Scleroderma Trials and Research (EUSTAR) database and found no association between anti-U1RNP autoantibodies and 3-year interstitial lung disease (ILD) progression or mortality in patients with systemic sclerosis–associated ILD (SSc-ILD).

“Anti-U1RNP autoantibodies, while common in mixed connective tissue disease, are also present in SSc patients and have been linked to more severe and early disease onset, including a higher prevalence of ILD,” wrote principal author Yannick Alladore, MD, of Cochin Institute, and coauthors. “However, the specific relationship between anti-U1RNP positivity and SSc-ILD has not been fully explored in large multicenter studies.”

Large Multicenter Cohort

The research team’s analysis included 6,043 patients with SSc-ILD from the EUSTAR database, 327  (5.4%) of whom tested positive for anti-U1RNP autoantibodies. 

Patients with anti-U1RNP positivity were younger (50.8 ± 15.1 vs 57.1 ± 13.3 years) and more often members of ethnic and racial minority groups (25.3% vs 5.0%), according to the authors. Patients with anti-U1RNP positivity also had higher rates of limited cutaneous involvement, joint synovitis, and myositis compared with patients who were anti-U1RNP negative. At baseline, anti-U1RNP positivity was associated with a lower forced vital capacity (FVC) (82.0% vs 86.0%) and diffusing capacity of the lungs for carbon monoxide (57.0% vs 60.5%) compared with anti-U1RNP negativity.

Comparable Decline Over Time

On examining ILD progression, the researchers discovered that 8.6% of patients with anti-U1RNP positivity exhibited major FVC decline (≥10%) at 1-year follow-up compared with 12.6% of patients who were anti-U1RNP negative. At 3 years, patients with anti-U1RNP positivity had 6 periods of major FVC decline among a total 75 periods (8.0%), and patients who were anti-U1RNP negative experienced 282 periods of major FVC decline among a total 2400 periods (11.8%).

“This difference was not statistically significant,” the authors noted.

According to study results, mortality rates mirrored these findings: 4.4% of patients with anti-U1RNP positivity died within 3 years compared with 6.6% of those who were anti-U1RNP negative.

Implications for Clinical Practice

“These findings suggest that while anti-U1RNP positivity is associated with certain clinical features in SSc-ILD, it does not appear to be associated with an increased risk of progressive lung disease …,” the researchers wrote, suggesting that anti-U1RNP should not, on its own, influence surveillance intensity or therapeutic escalation for patients with SSc-ILD. 

The team concluded that “further research is needed to explore the role of anti-U1RNP as a prognostic marker in SSc-ILD.”