TY - JOUR T1 - Frequency of positive ANCA test in a population with clinical symptoms suggestive of autoimmune disease and the interference of ANA in its interpretation JO - Reumatología Clínica (English Edition) T2 - AU - Romero-Sánchez,Consuelo AU - Benavides-Solarte,Mario AU - Galindo-Ibáñez,Isabel AU - Ospina-Caicedo,Ana Isabel AU - Parra-Izquierdo,Viviana AU - Chila-Moreno,Lorena AU - Villa,Amanda AU - Casas-Gómez,María Consuelo AU - Angarita,Ignacio AU - Bautista-Molano,Wilson AU - Romero-Álvarez,Verónica AU - Bello-Gualtero,Juan Manuel SN - 21735743 M3 - 10.1016/j.reumae.2018.09.015 DO - 10.1016/j.reumae.2018.09.015 UR - https://reumatologiaclinica.org/en-frequency-positive-anca-test-in-articulo-S2173574319301790 AB - BackgroundAntibodies against neutrophil cytoplasm (ANCA) are associated with vasculitis. There are different methods to determine their presence. The interference of antinuclear antibodies (ANA) in the differentiation between P-ANCA and C-ANCA patterns has been described. ObjectiveTo determine the frequency of ANCA in a population with manifestations of autoimmune disease, and evaluate the interference of ANA in its interpretation. Materials and methodsRetrospective, descriptive nonexperimental cross-sectional study, including 3330 data. The presumptive diagnosis was autoimmune disease and a test for ANCA was requested. The ANCA and ANA determinations were made by indirect immunofluorescence, L-ANCA® and CytoBead® ANCA. Anti-proteinase 3 and anti-myeloperoxidase were detected by ELISA and CytoBead® ANCA. ResultsANCAs were positive in 10.21% and 12.64% of those positive for ANCA were positive for ANA. The inter-rater agreement statistic (Kappa) for anti-PR3 between CytoBead ANCA and ELISA was 100% (K=1.00; P<.05) and the agreement between anti-myeloperoxidase by ELISA and CytoBead® ANCA was high (K=0.94; P<.05). 30% of those with ANCAs had a diagnosis of a type of vasculitis; 20% of them had an autoimmune disease. ConclusionsThe results suggest an overestimated request for ANCAs as a diagnostic aid in primary care which was not addressed. For an adequate evaluation of ANCAs, the indirect immunofluorescence technique should be implemented for the control and confirmation with the determination of specific antigens for anti-proteinase 3 and anti-myeloperoxidase in any of the confirmatory assays. The high concordance shown by ANCA CytoBeads makes us consider the use of this alternative for the determination of ANCAs and the confirmation. Given the interference of ANAs, the ANA test by IFI in the presence of positive P-ANCA results is recommended in order to minimise “false positives”. ER -