Background Therapeutic target in rheumatoid arthritis (RA) aims at achieving remission or low disease activity (1). Among the known poor prognostic factors are anti–citrullinated protein antibody (ACPA) and rheumatoid factor (RF). Clinical significance and therapeutic implications of the positivity of antinuclear antibodies (ANA) in serum of RA patients is still under debate.
Objectives The implications of ANA positivity, as a prognostic factor, in the therapeutic response to biologic therapy in RA, as measured by DAS28 score.
Methods Cross sectional, observational study; all data were gathered from the electronic database of Romanian Registry of Rheumatic Diseases (RRBR) which comprises all RA patients following biological treatment in the country. There were included only RA patients who were evaluated for the presence of ANA, before initiating biologic therapy.
Results 740 RA patients were included in the study, mean age 56.50 years (±12.59), 84.5% women, mean disease duration 12.54 years (±7.67), 66.4% from urban areas, 74.7% retired. At baseline (prior to biologic start), 26.9% patients were positive for ANA, 89.8% for RF and 37% for anti-CCP antibodies and the mean DAS28 was 5.09±2.35. 72.4% patients were treated with TNF-alpha blockers, while 27.6% with anti-CD20 drugs. During evolution, 22% of subjects required switch of therapy. Biologics persistency (the duration of therapy under one drug) was on average 31.70 (±29.95) months (for those without switch) and the latest DAS 28 score was 2.90±1.41. There were statistically significant differences between DAS28 values at all assessments, depending on the presence of ANA. At biological start, DAS28 score in ANA positive group was 5.70±2.06, while in ANA negative group was 4.86±2.41 (p<0.001). In terms of treatment efficacy, assessed by the latest DAS28, ANA positive group had a score of 3.32±1.61, compared to 2.74±1.30 of the ANA negative patients (p<0.001). The drug persistence in ANA positive patients was 22.65±25.68 months, versus 34.86±30.71 months in ANA negative group (p<0.001). For patients who required switch of therapy, DAS28 score at switch time was 5.42±1.52 in ANA positive group, versus 4.79±1.80 in ANA negative group (p=0.05). There is a poor positive association between ANA positivity and DAS28 at all assessments (r =0.2, p<0.01) and ACPA positivity (r =0.2, p<0.01) and a negative correlation between ANA positivity and drug persistence (r = - 0.2, p<0.01). Linear regression showed that ANA positivity best predicts the treatment efficacy, evaluated by DAS28 dynamics (t =4.5, p<0.001) (followed by ACPA positivity).
Conclusions ANA positivity in patients with RA, before initiating the biological therapy, may be a poor prognostic factor for the therapeutic efficacy, as well as for the drug persistence. More studies are needed to confirm these observations.
Smolen JS, Landewe R, Breedveld FC, Buch M, Burmester G, Dougados M et al,EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2013 update Ann Rheum Dis. Mar 2014; 73(3): 492–509.
Disclosure of Interest None declared