GLASGOW, SCOTLAND – Two subtypes of the anti-Ro autoantibody that are commonly associated with primary Sjögren’s syndrome could possibly help to predict disease severity and clinical outcomes.
Interim data on the first 314 patients included in the UK Primary Sjögren’s Syndrome Registry (UKPSSR) showed that anti-Ro52 was associated with a reduced risk of articular manifestations, while anti-Ro60 was associated with cutaneous manifestations of the disease.
Patients who were positive for either antibody were at increased risk for increased disease activity in the biological domains. Neither subtype was associated with myositis nor liver involvement, however, which is in contrast to the findings of other studies.
"There has been quite a lot of controversy regarding whether there are associations [between anti-Ro] and particular clinical manifestations in primary Sjögren’s syndrome, or indeed in other autoimmune diseases," said Dr. Wan-Fai Ng, the chief investigator for the UKPSSR and clinical senior lecturer at Newcastle (England) University.
Dr. Ng presented the research on behalf of lead author Dr. Josephine Vila of Newcastle upon Tyne Hospitals NHS Foundation Trust, May 3, at the British Society for Rheumatology Annual Conference (Rheumatology. 2012;51:iii35, abstract O30).
The UKPSSR is a U.K.-based cohort and biobank of more than 600 people diagnosed with primary Sjögren’s syndrome (Rheumatology. 2011;50:32-9). Patients have been recruited from 32 centers and have been assessed prospectively using standardized criteria and validated tools such as the Sjögren’s syndrome clinical activity index (SCAI) and Sjögren’s syndrome damage index (SSDI).
Previous research has suggested anti-Ro 52 may be associated with an increase in muscle and liver problems, whereas anti-Ro60 may be associated with a lower likelihood of liver involvement. Anti-Ro52 has also been associated with Sjögren’s syndrome while anti-Ro60 has been associated with systemic lupus erythematosus.
Conflicting data, however, led Dr. Vila and her team to explore the associations between the anti-Ro autoantibody subtypes and clinical manifestations in primary Sjögren’s syndrome using data from the UKPSSR.
Anti-Ro52 and anti-Ro60 autoantibodies were measured prospectively in the serum of patients using a high-sensitivity assay. The EULAR Sjögren’s system disease activity index (ESSDAI) was then used to stratify patients according to 12 organ-specific domains, which mostly relate to clinical data (Ann. Rheum. Dis. 2010;69:1103-9).
A high percentage of patients were positive for the anti-Ro52 (81%) and anti-Ro60 (82%) autoantibodies. Very few patients were positive for only one of these autoantibodies, with just eight (2.5%) patients positive only for anti-Ro52 and 10 (3.1%) positive only for anti-Ro60. Forty-nine (15.6%) were negative for both.
The relative risk for articular manifestations with anti-Ro52 was 0.7 (95% confidence interval, 0.5-0.9; P = .039). There was an increased risk of biological manifestations (RR 4.6; 95% confidence interval, 2.3-9.2; P less than .0001). Patients with anti-Ro52 autoantibodies were also more likely than those without to have decreased tear expression with an abnormal Schirmer’s test (RR 1.6; 95% CI, 1.3-2.1; P less than .0001) and abnormal salivary flow (RR 1.13; 95% CI, 1.0-1.3; P = .042).
Cutaneous manifestations were increased in patients positive for anti-Ro60 (RR 6.9; 95% CI, 1.0-49.3; P = .037). This autoantibody was also associated with a higher risk of biological manifestations (RR 6.2; 95% CI, 2.7-14.5; P less than .0001) and an abnormal Schirmer’s test (RR 1.4; 95% CI, 1.1-1.7; P less than .0001).
In addition, anti-Ro52 was significantly associated with disease duration and fatigue (P = .034) and anti-Ro60 with ESSDAI.
"We have planned to look at the other autoantibodies and disease association as well, but we’d rather do it in the entire cohort," Dr. Ng commented.
Dr. Ng reported no financial disclosures or relevant conflicts of interest. The UKPSSR is funded by the UK Medical Research Council.