Background/Purpose: EULAR and ACR have jointly funded a project to improve existing SLE classification criteria, aiming at earlier and more accurate classification of the disease. This abstract reports on an early phase of that project. 

ANA constitute the immunological hallmark of SLE, and ANA testing is widely used for SLE diagnosis based on its reportedly high sensitivity. Although indirect immunofluorescence on Hep-2 cells (IIF-Hep2) is considered the gold standard of ANA testing (1), the performance of different ANA titers and the possibility of including positive ANA as an entry criterion for the classification of SLE have not been systematically evaluated. We therefore reviewed the literature on the performance of IIF-Hep2 ANA testing for the classification/diagnosis of SLE. 

Methods: A systematic literature search was conducted in MEDLINE, EMBASE and Cochrane trial database for articles published between January 1990 and March 2014. The research question was structured according to PICO (Population, Intervention, Comparator, Outcome) format rules, and PRISMA recommendations were followed where appropriate. Meta-regression analysis for diagnostic tests was performed using the ANA titer as independent variable and sensitivity and specificity as dependent variables.

Results: A total of 3919 publications were screened in abstract and title and 623 articles were evaluated in full-text. Of these, 61 matched the eligibility criteria and were included in the analysis. The included studies comprised 10,309 SLE patients in total, of whom 9,797 (95.0%) were reported to be ANA positive at various titers. For ANA at titers of 1:40, 1:80 and 1:160, meta-regression gave sensitivity values of 98.6% (95% confidence interval [CI] 97.7-99.1%), 97.9% (CI 96.9-98.6%) and 95.9% (CI 93.9–97.3%), respectively. The corresponding specificities were 72.5% (CI 63.8-79.7%), 79.6% (CI 72.4-85.3%) and 89.6% (CI 84.8-93.0%), respectively.

Conclusion: The results of this systematic literature search and meta-regression confirm the high sensitivity of a positive ANA test for SLE. However, a small subgroup of true ANA negative SLE patients suggests that positive ANA should not be an absolute entry criterion for classifying SLE, but that it might function well in a combined entry criterion, such as positive ANA and/or low complements.

Reference: (1)Agmon-Levin et al, Ann Rheum Dis 2014; 73: 17ff

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/anti-nuclear-antibodies-have-high-sensitivity-for-systemic-lupus-erythematosus-results-of-a-systematic-literature-review-and-meta-regression-of-diagnostic-data/