This study aimed to review and compare the diagnostic accuracy of the screening enzyme immunoassay (SEIA) and indirect immunofluorescence (IIF) as anti-nuclear antibody (ANA) screening assays for patients with systemic rheumatic diseases (SRDs), including systemic lupus erythematosus (SLE), Sjögren's syndrome (SS), and systemic sclerosis (SSc).
A systematic literature search was conducted in the Medline, Embase, Cochrane, Web of Science, and Scopus databases for articles published before August 2017. A bivariate random effects model was used to calculate pooled diagnostic values.
Thirty-three studies including 3976 combined SRDs, 2839 SLE, 610 SS, and 1002 SSc patients and 11,716 non-healthy and 8408 healthy controls were available for the meta-analysis. The summary sensitivities of SEIA vs. IIF were 87.4% vs 88.4% for combined SRDs, 89.4% vs. 95.2% for SLE, 88.7% vs. 88.4% for SS, and 85.4% vs. 93.6% for SSc, respectively. Meanwhile, the summary specificities of SEIA vs. IIF were 79.7% vs.78.9% for combined SRDs, 89.1% vs. 83.3% for SLE, 89.9% vs. 86.8% for SS, and 92.8% vs. 84.2% for SSc, respectively. Although the differences in sensitivity and specificity between SEIA and IIF were not significant in most subgroups, the summary sensitivity of SLE presented statistically significant changes.
Our systematic meta-analysis demonstrates that both SEIA and IIF are useful to detect ANAs for SRDs. Between the two assays, IIF is a more sensitive screening assay than SEIA, particularly in patients with SLE. SEIA is comparable to IIF, considering the specificity and standardization.