Low Prevalence of Anti-SSA/B in Women With Rheumatoid Arthritis Wishing to Conceive

While current advice recommends testing for anti-Sjögren's-syndrome-related antigen A (anti-SSA) and anti–Sjögren's-syndrome-related antigen B (anti-SSB) in patients with rheumatoid arthritis (RA) who would like to conceive, this practice should be reconsidered given the low prevalence of these antibodies, according to a study published in BMJ Journals.¹

Higher levels of anti-SSA have been linked to a higher risk of CHB and other cardiac complications. Additionally, higher titers of anti-SBB is linked to the non-cardiac elements of NLS. Due to this, preventive screenings have been utilized in high-risk populations to detect CHB as early as possible.

However, the association between anti-SSA antibodies and congenital heart block (CHB) or neonatal lupus syndrome (NLS) only occurs in 1%-2% of exposed fetuses.

“Only 1.5% of all [CHB] cases were observed in women diagnosed with RA. This observation was in line with previous literature, in which no maternal diagnosis of RA in children born with congenital cardiac manifestations related to anti-SSA were observed,” stated investigators.

The study was conducted using 2 cohorts, PARA cohort and PreCARA cohort, which analyzed RA and pregnancy. Further, investigators utilized the French national registry of NLS and CHB to determine the prevalence of maternal diagnosis of RA, which included both fetuses and children born to mothers with anti-SSA and/or anti-SSB antibodies. Eligible patients were over the age of 18 and gave their consent.

Blood was collected at each visit. The presence and levels of anti-SSA and anti-SSB was analyzed using fluorescence-enzyme immunoassay (FEIA) and the normal range was considered <7 units/mL.

Out of 647 patients with RA, 26 had anti-SSA and/or anti-SSB antibodies; 25 patients had anti-SSA (3.9%) and 7 had anti-SSB (1.1%). Only 13 participants had an anti-SSA level of >240 units/mL. The presence of these antibodies was more common in rheumatoid factor (RF)-positive patients (5.1%) when compared with RF-negative patients (1.6%). There were no cases of CHB or NLS in either cohort.

In the French national registry, 51 out of 195 mothers (26.3%) with CHB had an autoimmune disease. Only 3 (1.5% of the total population) had RA and no cases of NLS were born to mothers with RA.

Investigators note that due to the small number of patients with detectable antibodies, they were not able to perform a multivariate analysis. Additionally, they could not determine cut-off points for anti-SSA titers due to the lack of CHB cases in the 2 cohorts.

“Anti-SSA and anti-SSB have a low prevalence in patients with RA with a wish to conceive. Moreover, in the French national registry of NLS and CHB maternal diagnosis of RA was infrequent,” concluded investigators. “If our findings could be replicated in other studies, it is justified to critically review the current guidelines. Especially since the practical consequences of finding these antibodies is currently questioned.”

Reference:

Smeele HTW, Schreurs MWJ, Costedoat-Chalumeau N, Cornette JMJ, Dolhain RJEM. Low prevalence of anti-SSA (anti-Ro) and anti-SSB (anti-La) autoantibodies in female patients with rheumatoid arthritis with a wish to conceive. RMD Open. 2021;7(2):e001727. doi:10.1136/rmdopen-2021-001727