PREVALENCE OF ANTI-NUCLEAR ANTIBODY IN THE INDIAN POPULATION: A TERTIARY REFERENCE LABORATORY STUDY

ABSTRACT

Background: Autoimmune diseases are known to be the third leading cause of fatality and morbidity amongst the population of industrialized world. They account for 3-9% of health burden in general people, but information regarding prevalence of autoantibodies and autoimmune diseases in developing nations is scarce. To study the prevalence of Anti-nuclear antibodies, Aim: the total number and distribution of different tests used in the diagnosis of anti-nuclear antibody amongst Indian population, and correlate the findings from these tests with the clinical characteristics of the patients. Retrospective data was evaluated from a Global Reference Method: Diagnostic Laboratory in Mumbai, for a period of 6 years. This included a total of 285095 cases tested for ANA. ANA-IFA and ANA-ELISA were the screening tests used while ANA-ELISA Profile and ANA Blot were the confirmatory tests. ANA by IFA was the most preferred Results: screening test (88.73%) and ANA by Blot was the most preferred Confirmatory test (67.13%) based on their sensitivity and positive predictive value respectively. ANA-IFA showed positivity of 36.48% and ANA by ELISA test had positivity of 11.46%. In confirmatory testing, ANA Blot showed a positivity of 31.90% and ELISA Profile had 23.36% positivity. Females showed significantly higher positivity for both the screening test and Confirmatory tests than males (p<0.001). Screening by ANA IFA and Confirmatory by Conclusion: ANA Blot was the most preferred tests in our study population. These tests were found to be better for diagnosis, sub-syndrome categorization, prognosis, clinical follow-up and therapeutic strategies in various autoimmune disorders.