Autoantibody testing in myositis: an update.

Purpose of review: This review aims to provide an update on myositis autoantibody testing strategies. We have focussed on the reliability and usefulness of different myositis autoantibody detection methods, including commonly used solid phase immunoassays and newer discovery techniques.

Recent findings: Several studies have highlighted the limitations of currently available immunoassays, particularly when used in populations with low pretest probability and without supporting clinical evidence. While many autoantibodies, such as anti-Jo1, are detected with high sensitivity and specificity, the low incidence of myositis autoantibodies in tested populations reduces their positive predictive value. The low sensitivity of line immunoassays to detect key myositis autoantibodies, including anti-TIF1γ and rarer antisynthetase autoantibodies, is a concern.

Summary: Myositis autoantibodies are widely accepted as important clinical tools, and hence, there is a significant demand for reliable, accessible, and affordable detection methods. False positives and negative results have the potential to impact on patient care, particularly for malignancy and lung disease associated autoantibodies. Increased availability of myositis autoantibody testing has led to a rise in requests from a broader range of clinicians. It is critically important that clinicians are aware of specific limitations of tests and interpret results in the context of clinical findings.