Factors Associated With the Antinuclear Antibody Titer of Patients With Systemic Autoimmune Rheumatic Diseases After Treatment: A Retrospective Study

Abstract Background: Antinuclear antibodies (ANAs) are a serological hallmark of systemic autoimmune rheumatic diseases (SARDs); however, few studies have investigated their post-treatment levels.Objective: The mechanism by which ANA titers are upregulated in SARDs remains unclear. We assessed factors associated with the ANA titer after treatment.Methods: 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.Results: 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. Men were twice as likely to achieve a decrease in the serum ANA titer than women (P = 0.055), and younger patients (<20) were 3× more likely to experience such a decrease (P = 0.005) compared to older patients (≥60 years). A baseline ANA titer >1:10000 was associated with a significantly lower (47×) serum ANA titer compared with the baseline ANA titer at a dilution of 1:100 (P < 0.001).. Homogeneous (P = 0.095) and cytoplasmic speckled (P = 0.158) had over threefold greater decrease in the serum ANA titer compared with other patterns.Conclusion: We found that a decrease in the serum ANA titer at 12 months after treatment for SARDs is associated with age, sex, ANA baseline titers, and ANA pattern.