To elucidate the possibility that autoantibodies to filaggrin, detected in patients with early RA (having a disease duration of not more than one year), may predict joint destruction assessed after five years of observation.
This is a 5 yr extension of a previous study (1) of 112 consecutive patients with early RA. Serum antifilaggrin autoantibodies were detected by immunoblotting (AFA) and by indirect immunofluorescence ("AKA"). DAS28, pain on a VAS. HAQ, and CRP were measured. Plain X-ray films were taken from hands and forefeet and a Larsen score was calculated.
Ninety-two of the original 112 patients had baseline X-rays available and constituted the study material. At 5 year follow-up, 67 of these 92 have been assessed and for 63 of these X-rays were available. For the whole patient material, significant radiological progression, measured by Larsen scores, occurred while disease activity and function (pain VAS, DAS28, CRP, and HAQ) improved significantly over five years. The groups of patients having AFA or "AKA" at baseline had significantly (p=0.006 and p<0.001, respectively) higher Larsen scores five years later than the groups without these antibodies. No clear relation of these antibodies to disease activity or function was demonstrated, except that the group of patients with "AKA" had significantly higher median CRP (p=0,003) after five years.
The present study shows that antifilaggrin autoantibodies may predict radiological progression. The prognostic value of these antibodies will be further evaluated in relation to other potential markers in a larger patient material.