POS0541 LOW PREVALENCE OF SSA (anti-Ro) AND SSB (anti-La) AUTOANTIBODIES IN FEMALE RHEUMATOID ARTHRITIS PATIENTS WITH A WISH TO CONCEIVE

Abstract

Background:The presence of SSA (anti-Ro) and SSB (anti-La) autoantibodies has important clinical implications for female patients with a wish to conceive. The association between maternal levels of these autoantibodies and complete congenital heart block and neonatal Lupus syndrome is well established. Currently guidelines advise to test for these antibodies in all Rheumatoid Arthritis (RA) patients with a wish to conceive (1).Objectives:The objective was to determine the prevalence and titers of SSA and SSB autoantibodies in female patients with rheumatoid arthritis and a wish to conceive or who are pregnant.Methods:Patients were derived from 2 large prospective cohorts on RA and pregnancy (PARA-cohort and PreCARA-cohort). The presence and titers of SSA and SSB were tested using Phadia, an automated system which uses fluorescence enzyme immunoassays (FEIA) (Thermo-Fisher Scientific).Results:We included a total of 647 patients with RA and a wish to conceive, 417 (64.5%) conceived during the follow-up period. A detailed description of the study population, stratified for the presence of SSA and SSB antibodies autoantibodies is presented in table 1. A total of 25 out of 647 patients had detectable SSA or SSB antibodies: SSA n = 25 (SSA-52 n = 17, SSA-60 n = 19), SSB n = 7. This corresponds with a prevalence of 3.9% for SSA antibodies and 1.1% for SSB antibodies. 13 (52% of the SSA positive patients, 2.0% of the total population) patients had a titer of >240 units/ml of SSA antibodies, and 3 (42.9% of the SSB positive patients, 0.46% of the total population) patients had a titers >340 units/ml of SSB antibodies. The percentage of patients positive for RF antibodies was higher in SSA and/or SSB positive patients (p = 0.01).Table 1.Clinical and demographic features from 647 patients with rheumatoid arthritis and a wish to conceive.VariableSSA and SSB antibodies [-], n = 622Positive SSA and/or SSB antibodies [+], n = 25p-valueAge at inclusion in the cohort (y, SD)32.3 (4.0)32.3 (4.4)0.98Median disease duration at first visit, years (IQR)5.2 (2.2 – 9.8)4.9 (2.1 – 11.4)0.77ACPA positive, n (%)408/614 (66.5)16 (69.6)0.75Rheumatoid Factor positive, n (%)426/617 (69.0)23 (92.0)0.01Conclusion:Our study shows an overall low prevalence of SSA and SSB autoantibodies in female RA patients with a wish to conceive. Moreover, about half of the patients positive for SSA or SSB had, based on literature, moderate or low titers of these antibodies (2). Especially for RF negative patients, the current advise to test for SSA and SSB antibodies in all RA patients with a wish to conceive should be reconsidered.