Objective. To investigate whether subfamilies of the RA-specific autoantibodies to human citrullinated fibrinogen (AhFibA) differentially associate with the RA risk factors, HLA-DRB1 shared epitope containing alleles (SE alleles) and cigarette smoking, and thus help to predict the disease outcome.
Methods. AhFibA and their anti-α36-50Cit and anti-β60-74Cit subfamilies were assayed by ELISA, at baseline, in the French ESPOIR (Etude et Suivi des Polyarthrites Indifférenciées Récentes) cohort composed of undifferentiated arthritides and RA patients of < 6 months’ duration. Cigarette smoking, SE alleles’ presence, DAS28, HAQ and modified Sharp–van der Heijde Score data were obtained at baseline, and after follow-up.
Results. After 3 years, 701 patients were classified as having RA according to the ACR/EULAR 2010 criteria. Among them, 349 (50%), 203 (29%) and 257 (37%) were AhFibA-, anti-α36-50Cit- and anti-β60-74Cit-positive, respectively. The presence and titres of AhFibA and their subfamilies similarly associated with SE alleles, irrespective of their fine specificity, without significant effect of smoking. Neither their presence nor their titre was associated with DAS28 or HAQ. The presence of at least one subfamily was associated with a faster Sharp/van der Heijde score progression, albeit without correlation with the titre.
Conclusion. AhFibA and their main subfamilies are similarly associated with SE alleles without additional effect of smoking. Whatever their fine specificity was, their presence (but not their titre) similarly constituted a marker of faster joint destruction.