Background/Purpose: Anti-SSA (Ro52/Ro60) and anti-SSB autoantibodies are the cardinal serological markers for SjogrenÕs syndrome. They are also present in other systemic autoimmune diseases. There is a limited data on their prevalence in systemic sclerosis (SSc).  The objectives of this study were to: 1) determine the prevalence of SSA (Ro-52 and Ro-60) and SSB antibodies in consecutive SSc patients using immunoprecipitation (IP) testing, and 2) compare the clinical features and survival among these subsets of SSc patients.

Methods: We studied an inception cohort of consecutive new SSc patients first evaluated at the UPMC Scleroderma Center between 2006 and 2011.  All patients underwent complete serologic testing using ANA, protein, and RNA immunoprecipitation (IP) testing to detect SSc-associated antibodies, Ro52, Ro60 and SSB antibodies.  Prevalence, demographic, clinical features, and survival were compared between SSA/SSB positive and negative SSc patients.  Statistical analyses were done using SAS 9.4. 

Results:

There were 474 patients met the inclusion criteria.  The mean age of cohort at first SSc visit was 53.7± 14.9 years, 79% were female, 90% were Caucasian, and 40% had diffuse skin thickening.  Of all patients, 65 (14%) were positive for anti-SSA/SSB antibodies (22 had Ro-52, 45 had Ro-60, and 2 had both, 4 had SSB). There was no patient with SSB-only serotype. There were no significant differences in demographics and frequency of major SSc-related internal organ involvement between seropositive and seronegative groups (Table 1). SSA/SSB positive patients had higher frequency of overlap syndrome (22% vs. 13%, p=0.05). The distribution of other SSc-associated autoantibodies did not differ. Over time, SSA/SSB positive patients developed higher rates of photosensitivity (9% vs 4%; p=0.03) and peripheral neuropathy (16% vs 7%; p=0.02). Among the SSA/SSB subsets, Ro-60 only patients developed more frequent gastrointestinal involvement compared to Ro52-only and seronegative patients (85% vs. 37% vs. 75%; p=0.001). No other clinical or serological differences existed between these three groups. Five-year survival was not significantly reduced in the SSA/SSB positive group (p=0.38)

Conclusion:   In this inception cohort of SSc patients, 14% had SSA/SSB antibodies.  These patients at presentation were less likely to have key phenotypic features of SjogrenÕs syndrome compared to seronegative patients.  The seropositive group developed more photosensitivity and neuropathy over time; however, objective SjogrenÕs evaluation testing was not performed systematically.  A previously unreported association of GI complications and Ro60 status was observed. Further studies are needed to confirm this association.

Table I. First SSc center visit characteristics of SSc with and without anti-SSA/SSB antibodies

*=abnormal objective motility testing or use of antibiotics for small bowel bacterial overgrowth