Background Recently, it was reported that the antinuclear antibody (ANA) before starting anti-TNF treatment or development of ANA might be related with clinical response of TNF inhibitors or side effect of infusion reactions.
Objectives The aims of this study were to examine the prevalence of positive ANA before starting TNF inhibitors in patients with RA and to investigate the impact of ANA positivity on persistency of anti-TNF treatment.
Methods Among 355 RA patients who started their first TNF inhibitor between 2000 and 2011, 273 patients who had performed ANA test before starting anti-TNF treatmentwere identified in theretrospective biologics registry in Korea of REtrospective study for Safety and Effectiveness of anti-RA treatment with biologiCs (RESEARCh). We classified all patients into two groups according topositivity of ANA; positive group (ANAtitres at a dilution ≥1:160) and negativegroup (ANAtitres <1:160). The period of observation for evaluating drug survival was defined as the time between starting of TNF inhibitors and their discontinuation or their last study visit if they continued therapy. Kaplan-Meier survival analysis was used to assess persistence, log-rank tests were used to compare drug survival between ANA positive and negative groups, and Cox proportional hazards models were used to assess whether ANA positivity is a potential predictor of treatment discontinuation.
Results Among 273 RA patients (mean age of 47.9 years and 85% of female), 131 (48%) patients were ANA positive before starting TNF inhibitors. At the baseline, ANA positive group was more commonly positive with rheumatoid factor (80% vs. 65%, p<0.01) and had higher disease activity with DAS 28 (6.2±0.9 vs. 5.9±0.9, p<0.01) compared to ANA negative group, while other potential predictors were comparable between two groups. In both groups, there was no significant difference in drug discontinuation rates due to all causes (P=0.97), side effects (p=0.83), and non-effectiveness (p=0.67). Cox-proportional hazards models showed that ANA positivity was not a risk factor for discontinuation due to all causes (OR 1.02, CI 0.63-1.65), side effects (OR 1.00, CI 0.98, 1.02), and non-effectiveness (OR 1.00, CI 0.97, 1.02).
Conclusions The prevalence of ANA positivity in RA patients who started TNF inhibitors were 48% and ANA positive patients had higher disease activity and RF positivity compared to ANA negative RA patients. However, ANA positivity was not associated with TNF inhibitor discontinuation due to overall causes, side effects, and non-effectiveness.
Acknowledgements This study was supported by a grant of the Korea Healthcare technology R&D Project, Ministry of Health and Welfare, Republic of Korea.(HI10C2020).
Disclosure of Interest None declared