Background Erosions are the hallmark of rheumatoid arthritis (RA). Although most of erosions may occur within 2 years of onset of the disease, their progression does not correlate with the duration of RA. Moreover, information about non-erosive RA is ambiguous.
Objectives To evaluate the prevalence and characteristics of non-erosive RA.
Methods Since no agreement about the time-lag interval for erosions appearance in RA exists, and there is no universally accepted definition about it, a zero score in hands and feet X-ray at 5 years of RA duration (by SvHD) was arbitrary considered as cut-off. Therefore, patients meeting these criteria were searched in a large cohort of RA patients (ACR, 1987). Metacarpophalangeal and metatarsophalangeal joints as well as wrist ultrasound (US) imaging (by OMERACT), and computed tomography (CT) were performed to confirm non-erosive RA. Spearman correlation coefficient, kappa analysis and Kendall´s W test were used to analyze data.
Results Out of a total of 800 RA patients, 38 met inclusion criteria (4.75%). Most of them were women (76.3%). The median (IQR) of the age and duration of the disease were 52 (13) and 10 (8) years, respectively. Rheumatoid factor (RF) and anti-CCP antibodies were positive in 86.8% and 55.3%, respectively. Non-erosive RA was confirmed by the three methods in only 7 patients. There was no concordance between the three methods. For this sample, the sensitivity and specificity were 70% and 52% for US, and 58% and 57% for CT, respectively. Non-erosive RA was positively although weakly correlated with improved functional class according to the HAQ (r=0.32, p=0.045) and ANA positivity (r=0.43, p=0.030), and negatively correlated with activity of the disease (by RAPID3, r= -0.32, p=0.05), the use of biological therapy (r= -0.31, p=0.05) and RF (r= -0.36, p=0.042).
Conclusions Non-erosive RA is rare (0.87%). A good functional class, ANA positivity, RAPID3 score, the use of biological therapy and RF influence the absence of erosions in long-standing RA (i.e., 5 years). Since there is a high variability and a lack of concordance exists among the imagining techniques, a consensus and unified definition about non-erosive RA are warranted.
Disclosure of Interest None Declared