A Preliminary Study for Applying Antiperinuclear Antibody Test to 2010 ACR/EULAR Classification Criteria for Rheumatoid Arthritis

ABSTRACT

BACKGROUND: The American College of Rheumatology/European League against Rheumatism classification criteria for rheumatoid arthritis (ACR/EULAR criteria) include the rheumatoid factor (RF) test and the anti-citrullinated peptide/protein antibody (ACPA) test as serologic makers for rheumatoid arthritis. Antiperinuclear factor (APF) test, an originator of ACPA, is highly specific for rheumatoid arthritis and can be detected in RF or anti-cyclic citrullinated peptide (anti-CCP) negative rheumatoid arthritis, but it is not included in the serologic criterion of ACR/EULAR criteria. In this study, we investigated the way for applying the APF test to ACR/EULAR criteria. METHODS: We analyzed clinical symptoms and laboratory findings of 53 patients who were suspected having rheumatoid arthritis. All patients were negative for the RF and anti-CCP and positive for APF. We classified these patients into 4 groups according to the fluorescence intensity of APF test, and gave 1-4 points for APF positivity. The proportion of patients who scored 6 or greater in ACR/EULAR criteria in relation to APF scores was evaluated. RESULTS: Median scores of ACR/EULAR criteria showed a tendency to increase as the level of fluorescence intensity of APF rises, but ACR/EULAR scores of 4 groups were not different significantly from each other (P>0.05). The proportion of patients who scored 6 or greater in ACR/EULAR criteria were 39.6% and 77.4%, when scores of APF positivity were 2 and 3 points, respectively. CONCLUSIONS: We think it is reasonable to include APF test in the ACPA of ACR/EULAR criteria and give 3 points for APF positivity, regardless of its fluorescence intensity.