AB0270 POSITIVE ACPA WITHOUT EVIDENCE OF ARTHRITIS – A RARITY?
Authors: Daniela Martins, Graça Sequeira
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Rheumatoid Arthritis (RA) follows a variable disease course in regards to joint damage and functional outcome, therefore an early diagnosis is crucial for its management. However, occasionally, this diagnosis can be a challenge. Rheumatoid Factor (RF) and Anti-citrullinated peptide antibodies (ACPA) are the most useful biomarkers in the diagnosis of RA and, although individually they do not dictate the final diagnosis, they present high specificity and may be positive even before clinical manifestations of the disease occur. ACPA is detected in approximately two thirds of the patients with RA and presents a superior diagnostic specificity when compared to RF. This specificity of 95-98% may present an increased value if it is three times superior to its value of reference. <h3>Objectives</h3> Share with the medical community and alerting them for the existence of patients with positive ACPA with no clinical evidence of RA. <h3>Methods</h3> By consulting the electronic clinical records of patients observed by a Rheumatologist, we identified and analyzed the patients that presented positive ACPA in their blood tests and no evidence of signs or symptoms of RA, during at least six years of follow-up. Patients with other rheumatic diseases, history of tuberculosis or chronic pulmonary diseases were excluded. <h3>Results</h3> We identified seven patients (average of 61 years old) with positive ACPA in at least two different blood tests, of which five presented a value three times superior to its normal value (&lt;15UA/mL). It should be noted that, four patients presented both positive ACPA and RF. Clinically, all patients referred mechanical symptoms that varied between cervical, low back, shoulder and knee pain and did not present any record of swollen joints without trauma. Radiologically, in most cases we observed joint degenerative damage. Six years after the first positive ACPA, none of the patients developed any manifestation of inflammatory joint disease. <h3>Conclusion</h3> Studies reveal that positive ACPA in healthy patients may precede the clinical diagnosis of RA. The specificity of positive ACPA and RF one and a half years before the diagnosis of RA is approximately 99-100%. However, as we demonstrated, it is not uncommon to find during clinical practice individuals with positive ACPA without evidence of arthritis, which leads us to emphasize the importance of a detailed anamnesis with a meticulous physical examination before establishing a diagnosis based on the patient's blood tests. <h3>References</h3> [1] Moeez S, et al. Anti-citrullinated protein antibodies: role in pathogenesis of RA and potential as a diagnostic tool. Rheumatol Int. 2013;33(7):1669–73 [2] Brito Rocha, et al. Clinical and pathophysiologic relevance of autoantibodies in rheumatoid arthritis. Advances in Rheumatology. 2019;59:2 [3] Nielsen SF, et al. Elevated rheumatoid factor and long term risk of rheumatoid arthritis: a prospective cohort study. BMJ. 2012;345:e5244 [4] RantapÄÄ-Dahlqvist S. What happens before the onset of rheumatoid arthritis?Curr Opin Rheumatol. 2009;21:272 [5] Bugatti S, et al. The Clinical Value of Autoantibodies in Rheumatoid Arthritis. Front. Med. 2018;5:339 [6] Avouac J, et al. Diagnostic and predictive value of anti-cyclic citrullinated protein antibodies in rheumatoid arthritis: a systematic literature review. Ann Rheum Dis2006; 65:845 <h3>Disclosure of Interests</h3> None declared