Systemic autoimmune rheumatic diseases (SARDs) are diverse and complex inflammatory illnesses characterised by the production of autoantibodies leading to destruction of tissues and organs. The heterogeneity and ambiguity of signs and symptoms such as inflammation, fatigue, and arthralgia makes diagnosis challenging. In addition, SARDs are uncommon conditions meaning most physicians have little experience in identifying specific diseases and instead rely on an antinuclear antibody (ANA) screen for potential direction of treatment. Systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and Sjögren syndrome (SjS) are discussed in this review due to the current practice by some Irish hospitals of screening for ANAs in these particular conditions. Indirect immunofluorescence assay (IIFA) using Hep-2 cells as a substrate is considered the ‘gold standard’ for ANA screening and was traditionally used in clinical settings, however this has been superseded by automated immunoassays enabling the processing of a high volume of samples. One such immunoassay is EliA™ connective tissue disease (CTD) screen which contains 17 antigens that are targets for ANAs. EliA™ CTD screen has generally been shown to have greater specificity and lower sensitivity than IIFA as a result of fewer antigens, although EliA™ CTD screen has shown to have a higher sensitivity in SjS. Overall, EliA™ CTD screen is a suitable screening test for SARDs since its sensitivity is only marginally worse than observed with IIFA and specificity is greater. This is important in reducing unnecessary further testing for more specific extractable nuclear antigens.
"A Review of Systemic Autoimmune Rheumatic Diseases and Analysis of Antinuclear Antibody Testing Methods and Clinical Utility of EliA CTD Screen,"
International Undergraduate Journal of Health Sciences: Vol. 3:
1, Article 7.
Available at: https://sword.cit.ie/iujhs/vol3/iss1/7