The impact of antinuclear antibody testing on the naming and misnaming of disease
The naming of an illness is an essential element in the care of patients and often depends on laboratory testing. Among tests to evaluate for possible autoimmunity, the antinuclear antibody (ANA) provides information that can be difficult to interpret and, thereby, can contribute to misnaming of certain signs and symptoms as an autoimmune disease, especially systemic lupus erythematosus (SLE). Although a positive ANA test is now considered necessary for the classification (diagnosis) of SLE, as many as 20% of the otherwise healthy population has a positive test. Furthermore, since ANA positivity can predate the diagnosis of SLE by many years, it is difficult to ignore a positive result even if ordered with a low pretest probability. Current technology allows for more complete and quantitative ANA profiling; such information could help determine the probability for disease, underpinning a potentially more informative approach for screening, prevention, and naming of disease.