Multiple autoantibody positivity linked to increased radiographic progression in early RA
medwireNews: Individuals with a wide range of anti-modified protein antibodies (AMPAs) experience higher rates of early radiographic progression than those with just a single antibody type, show data from the Scottish Early Rheumatoid Arthritis inception cohort.
Karim Raza (University of Birmingham, UK) and co-investigators say their study “suggests that the optimal prediction of future rates of radiographic progression in patients with rheumatoid arthritis will require an assessment of autoantibodies against multiple post-translationally modified proteins or peptides.”
Of 221 patients with newly diagnosed rheumatoid arthritis (RA) or undifferentiated arthritis, 21.7% were positive for anti-citrullinated peptide antibodies (ACPAs), 13.1% were positive for ACPAs and anti-acetylated peptide antibodies (AAPAs), 43.9% were positive for ACPAs, AAPAs, and anti-carbamylated peptide antibodies, and 21.3% were seronegative for all three AMPA groups.
The researchers report in The Lancet Rheumatology that radiographic progression at the hands and feet, as measured by the change in total Sharp-van der Heijde (SvH) score from baseline to 12 months, was significantly greater among individuals positive for all three antibody types relative to those only positive for ACPAs, with estimated mean increases of 1.8 and 0.5 points, respectively.
Conversely, there was no significant difference in the change in total SvH score between the ACPA-positive and seronegative groups, at 0.5 versus 0.7 points.
Raza and team say this suggests “that the effect on radiographic progression of being ACPApositive is restricted to those patients who also have other AMPAs.”
There was no difference in the change in joint space narrowing score among the antibody groups, but individuals in the triple-positive group had a significantly greater change in erosion score than those only positive for ACPAs (1.1 vs 0.2 points).
Of note there was no significant difference in the average age at recruitment, disease duration, HAQ-DI score, Hospital Anxiety and Depression Scale score, EQ5D score, and disease activity among any of the antibody groups.
In addition, numerically fewer patients in the singlepositive group than in the triplepositive group were receiving three or more conventional DMARDs, which indicated that the differences in radiographic progression were not “a consequence of triplepositive patients receiving less intense therapy,” the researchers remark.
Raza et al conclude: “We believe that further prospective work is required to understand the effects of multiple autoantibody specificities in patients with rheumatoid arthritis and whether such baseline autoantibody status should be used to stratify patients with rheumatoid arthritis in therapeutic trials.”
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