Antinuclear antibody screening by ELISA and IF techniques: discrepant results in juvenile idiopathic arthritis but consistency in childhood systemic lupus erythematous

Abstract

Lately, many hospital laboratories are using for antinuclear antibody (ANA) screening the solid-phase immunoassays (ELISA-ANA) instead of the traditional immunofluorescence ANA test (IF-ANA). Results of previous studies that compare the two technologies show poor correlation between them in both juvenile idiopathic arthritis (JIA) and childhood lupus erythematous (SLE) patients. In this study, we investigated whether ELISA-ANA and traditional IF-ANA results are comparable in pediatric patients with different rheumatic diseases. A total of 156 consecutive patients were included in the study-90 children with JIA, 33 with reactive arthritis, 19 with SLE, 4 with idiopathic chronic uveitis, and 10 with other systemic rheumatic diseases. ANA determination was performed using both assays. The higher rate of discrepancies between the two methods of ANA screening appeared in the JIA population (19/90, p < 0.001). All JIA patients with false-negative results by ELISA had significant or high IF-ANA titres. The prevalence of JIA-associated uveitis was higher in the group of false-negative ELISA-ANA children than in the ELISA-positive patients but without statistical significance (p = 0.62). On the contrary, in SLE group, the consistency rate of the two assays was 100%, and the reactivity levels of ELISA-ANA were significantly higher than in ELISA-positive JIA patients (p < 0.001). ELISA seems to be a reliable method for screening ANA in childhood SLE, but not in JIA. Limited by the few SLE patients, our findings need further consideration.