High Prevalence of ILD With Anti-Ro/SSA Antibodies in SSc
At baseline, patients with anti-Ro/SSA antibodies were aged 55-56 years, 84%-87% were women, and muscular involvement was present in 18% of patients positive for anti-Ro/SSA antibodies and 12.5% of those who were negative (P < .001). According to HRCT, ILD was present in 56.2% of patients positive for anti-Ro/SSA antibodies and in 47.8% of those who were negative (P = .001). FVC% was 92.5% in patients positive for anti-Ro/SSA antibodies and 95.7% in those who were negative (P = .002). DLCO% was 66.9% in patients positive for anti-Ro/SSA antibodies and 71% in those who were negative (P < .001).
“A total of 15% of all SSc patients presented as positive for anti-Ro/SSA antibodies, and these patients all presented with higher prevalence of SSA-nonspecific antibodies, too: Of note, those with anti-La/SSB and anti-U1/RNP and rheumatoid factor,” Dr. Burja reported.
In patients with anti-U1/RNP autoantibodies, 1% were positive and 4% were negative for anti-Ro/SSA antibodies; in those with anti-La/SSB autoantibodies, 17% were positive and 1% were negative for anti-Ro/SSA antibodies; and in those with rheumatoid factor, 28% were positive and 14% were negative for anti-Ro/SSA antibodies.
Dr. Burja pointed out that the average disease duration in the study cohort at baseline was 7 years, “and at this timepoint, we expect to see some common disease manifestations. Specifically, higher muscular involvement and higher ILD based on HRCT.
“We decided to focus on patients with established ILD at baseline,” said Dr. Burja. “Anti-Ro/SSA-positive patients with established ILD at baseline presented with lower DLCO values at 59% in patients positive for anti-Ro/SSA antibodies and 61% for those who were negative.”
After conducting a multivariable analysis of 14,066 healthcare visits and adjusting for known risk factors for ILD, the researchers concluded that anti-Ro/SSA antibodies are an independent risk factor for ILD, with an odds ratio of 1.24 (95% CI, 1.07-1.44; P = .006). They also determined that anti-Ro/SSA antibodies are a risk factor for lower DLCO values in patients with ILD, with a regression coefficient of −1.93.
The researchers then explored the progression of ILD and overall disease progression and survival during the follow-up period in a longitudinal analysis. “However, anti-Ro/SSA antibodies were not found to predict the progression of ILD,” reported Dr. Burja, adding that this was true regardless of the definition of ILD progression used. “Nor did anti-Ro/SSA antibodies do not predict survival or overall disease progression.”
Dr. Burja pointed out the limitations in his study, including the lack of standardized criteria for all centers to assess anti-Ro/SSA positivity; there was a lack of discrimination between anti-Ro52 and anti-Ro60 subtypes, and there were no standardized applicable criteria to study lung progression in SSc.
Dr. Burja and Dr. Ospelt had no relevant financial disclosures.
A version of this article appeared on Medscape.com.