Evaluation of diagnostic tests for antinuclear antibodies in rheumatological practice

To investigate and compare the accuracy and usefulness of diagnostic tests for antinuclear antibodies (ANA) a cross-sectional study of sera derived fr om patients admitted to the Department of Rheumatology was tested for the p resence of ANA using either indirect immunofluorescence on HEp-2 cells, ind irect immunoperoxidase techniques on HEp-2 cells and mouse kidney, or two c ommercial enzyme-linked immunosorbent assays (ELISA). The diagnostic sensit ivity and predictive values of the tests were calculated and compared. The accuracy of tests was compared using receiver-operating characteristics (RO C) methodology. All ANA-positive sera were further analysed for the presenc e of antibodies against extractable nuclear antigens (anti-ENA) and anti-DN A. A moderate to good agreement was found between tests, with kappa ranging from 0.469 to 0.659. Highest sensitivity for systemic lupus erythematosus (SLE; 93.3%) and primary Sjogren's syndrome (SS; 70%) was found using immun ofluorescence on HEp-2 cells. Immunofluorescence on HEp-2 cells performed s tatistically better than the other tests in predicting SLE but not SS. All tests except mouse kidney showed good and comparable performance in detecti ng sera with anti-ENA and anti-DNA. At the given cut-off values indirect im munofluorescence on HEp-2 cells performed best. All assays except mouse kid ney showed performance characteristics sufficient for use in routine analys is of ANA.