Clinical importance of antinuclear antibody testing in a tertiary neuro-care center, India

Background: Antinuclear antibody (ANA) testing is the first test ordered in any patient suspected of autoimmune diseases. Often ANA indirect immunofluorescence (IIF) screening tests have high sensitivity because of high background, which can lead to erroneous clinical diagnosis and management when ordered unnecessarily. The following study was undertaken to envisage the clinical importance of ANA-positive test results among cases presenting to a tertiary neuro-care center. Methods: Present study is a secondary data analysis of 166 ANA IIF positive samples. Serum samples were further subjected to specific antigen detection by ANA immunoblot assay. The final diagnosis was reviewed in the context of descriptive data as to why testing was ordered. Results: The overall positivity rate of ANA for 3 years was 2.12%. The peripheral nervous system was most commonly involved accounting for 56 (33.73%) cases followed by the central nervous system in 40 (24.09%) cases and others. The predominant ANA pattern observed was speckled in 73 (43.9%) cases. On ANA profiling, reactivity to Ro52 (35 [40.22%]) was most common. Females were predominantly (70.5%) affected than males (29.5%). There was no association found in ANA pattern with age, sex, duration of illness, and the clinical disorder. Conclusions: ANA positivity is sporadically associated with nervous system autoimmune disorders. Screening tests like ANA can be judiciously employed for meaningful clinical interpretation of neurological diseases.