Evaluation of antinuclear antibody (ANA) in ANA-associated connective tissue diseases

Factors associated with the antinuclear antibody (ANA) titer of systemic autoimmune rheumatic diseases in ANA-positive patients after treatment: a retrospective study

Antinuclear antibodies (ANAs) are a serological hallmark of systemic autoimmune rheumatic diseases (SARDs); however, few studies have investigated their post-treatment levels. The mechanism by which ANA titers are upregulated in SARDs remains unclear. We assessed factors associated with the ANA titer after treatment. In this retrospective study, we analyzed the clinical database of Zhongshan Hospital, Medical College of Xiamen. Demographic data and baseline and 12-month post-treatment ANA titers were collected. Bivariate and multivariate analyses were performed to determine the factors associated with the ANA titer. This study identified 31,923 patients who underwent ANA assay for SARDs screening, and a total of 1043 patients were included in the study. Approximately 16% of the patients showed a decrease in the serological ANA titer. Younger patients (< 20) were 3 × more likely to experience such a decrease (P = 0.005) compared to older patients (≥ 60 years). Having a baseline ANA titer > 1:10,000 was associated with an increase likelihood of a decrease in the serological ANA titer compared with baseline ANA titer 1:10,000, 1:3200 and 1:1000 (P < 0.001). We found that a decrease in the serum ANA titer at 12 months after treatment for SARDs is associated with age and ANA baseline titers.

The concordance of serial ANA tests in an Australian tertiary hospital pathology laboratory

The antinuclear antibody (ANA) tests are some of the more frequently requested tests for the diagnosis of autoimmunity. Although they are used primarily as diagnostic blood tests, multiple requests on the same patient continue to be encountered in the laboratory. This retrospective analysis of serial ANA testing at one pathology laboratory in Australia is the first study that examines the statistical concordance and possible implications of this on clinical practice. High-titred ANA have quite good repeatability for titre and pattern, and low-titred ANA, which can be non-specific, have poor repeatability. Staining patterns are, in general, almost random in nature on serial tests when compared to the first-obtained ANA pattern for each patient. This study confirms that there is little benefit in serial ANA testing, and only if there is a clear change in the patient's clinical picture would repeat of an initial low-titred ANA be useful. The findings reinforce the need for pathology stewardship to minimise costs, wasted resources and unnecessary referrals.