Anticarbamylated protein antibodies are associated with long-term disability and increased disease activity in patients with early inflammatory arthritis: results from the Norfolk Arthritis Register. Issue 6 (6th October 2015)

• Record Type: Journal Article
• Authors: Humphreys, Jennifer H; Verheul, Marije K; Barton, Anne; MacGregor, Alexander J; Lunt, Mark; Toes, Rene EM; Symmons, Deborah PM; Trouw, Leendert A; Verstappen, Suzanne MM
• Is Part Of: Annals of the rheumatic diseases. Volume 75:Issue 6(2016)
• Page Start: 1139
• Page End: 1144
• Publication Date: 2015-10-06
• Subjects: Early Rheumatoid Arthritis -- Disease Activity -- Autoantibodies -- Epidemiology -- Rheumatoid Arthritis; Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2015-207326
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Objectives: Anticarbamylated protein (anti-CarP) antibodies are a novel family of autoantibodies recently identified in patients with inflammatory arthritis. The aim of this study was to investigate their association with long-term outcomes of disability and disease activity over 20 years' follow-up in a cohort of patients with inflammatory polyarthritis (IP). Methods: Norfolk Arthritis Register recruited adults with recent-onset swelling of ≥2 joints for ≥4 weeks from 1990 to 2009. At baseline, Health Assessment Questionnaire (HAQ) and 28 joint disease activity scores (DAS28) were obtained, and C reactive protein, rheumatoid factor (RF), anticitrullinated protein antibodies (ACPA) and anti-CarP antibodies were measured. Further HAQ scores and DAS28 were obtained at regular intervals over 20 years. Generalised estimating equations were used to test the association between anti-CarP antibody status and longitudinal HAQ and DAS28 scores; adjusting for age, gender, smoking status, year of inclusion and ACPA status. Analyses were repeated in subgroups stratified by ACPA status. The relative association of RF, ACPA and anti-CarP antibodies with HAQ and DAS28 scores was investigated using a random effects model. Results: 1995 patients were included; 1310 (66%) were female. Anti-CarP antibodies were significantly associated with more disability and higher disease activity, HAQ multivariate β-coefficient (95% CI) 0.12 (0.02 to 0.21), and these associations remained significant in the ACPA-negative subgroups. The associations of RF, ACPA and anti-CarP antibodies were found to be additive in the random effects model. Conclusions: Anti-CarP antibodies are associated with increased disability and higher disease activity in patients with IP. Our results suggest that measurement of anti-CarP antibodies may be useful in identifying ACPA-negative patients with worse long-term outcomes. Further, anti-CarP antibody status provided additional information about RF and ACPA.