The antinuclear antibody assay: developing criteria for reflexive anti-dsDNA antibody testing in a laboratory setting

Background: We examined the relationship between antinuclear antibody (ANA) data and the presence of anti-double stranded DNA antibodies (anti-dsDNA). Methods: De-identified demographic, ANA and anti-dsDNA data were available for 30,196 individuals aged ≥20 years, whose sera were submitted sequentially to our laboratory. When multiple sera were received for the same subject, data from the earliest sample were used. Anti-dsDNA frequency was stratified by ANA titer and pattern, sample referral source, and by the patient's age, gender, and diagnosis. Results: For sera with ANA titer ≥256 and an accompanying diagnosis of systemic lupus erythematosus, anti-dsDNA frequency was 53.7%, 35.3%, and 37.5% for homogeneous, speckled, or multiple ANA patterns, respectively. Among remaining sera with ANA titer ≥256, anti-dsDNA frequency was highest for the homogeneous pattern (15.9%). Anti-dsDNA frequency was three-fold higher among sera submitted by rheumatologists compared with other providers. However, its relative distribution by ANA pattern and titer was similar between these groups. Patient age and gender had no significant effect on anti-dsDNA frequency after ANA data were taken into account. Conclusions: ANA pattern and titer, together with the diagnosis submitted with the serum sample, can be used to guide decisions for reflexive anti-dsDNA testing in a clinical laboratory setting.