Performance of Antinuclear Antibodies for Classifying Systemic Lupus Erythematosus: A Systematic Literature Review and Meta-Regression of Diagnostic Data

Objective: To review the published literature on the performance of indirect immunofluorescence (IIF)–HEp-2 antinuclear antibody (ANA) testing for classification of systemic lupus erythematosus (SLE). Methods: A systematic literature search was conducted in the Medline, Embase, and Cochrane databases for articles published between January 1990 and October 2015. The research question was structured according to Population, Intervention, Comparator, Outcome (PICO) format rules, and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations were followed where appropriate. Meta-regression analysis for diagnostic tests was performed, using the ANA titer as independent variable, while sensitivity and specificity were dependent variables. Results: Of 4,483 publications screened, 62 matched the eligibility criteria, and another 2 articles were identified through reference analysis. The included studies comprised 13,080 SLE patients in total, of whom 12,542 (95.9%) were reported to be IIF-ANA positive at various titers. For ANA at titers of 1:40, 1:80, 1:160, and 1:320, meta-regression gave sensitivity values of 98.4% (95% confidence interval [95% CI] 97.6–99.0%), 97.8% (95% CI 96.8–98.5%), 95.8% (95% CI 94.1–97.1%), and 86.0% (95% CI 77.0–91.9%), respectively. The corresponding specificities were 66.9% (95% CI 57.8–74.9%), 74.7% (95% CI 66.7–81.3%), 86.2% (95% CI 80.4–90.5%), and 96.6% (95% CI 93.9–98.1%), respectively. Conclusion: The results of this systematic literature review and meta-regression confirm that IIF-ANAs have high sensitivity for SLE. ANAs at a titer of 1:80 have sufficiently high sensitivity to be considered as an entry criterion for SLE classification criteria, i.e., formally test other classification criteria for SLE only if ANAs of at least 1:80 have been found.