Clinical predictors of erosion-free status in rheumatoid arthritis: a prospective cohort study

Abstract

Objective. Treatment algorithms in RA include factors associated with poor prognosis; however, many patients remain erosion free despite years of disease. Our objective was to characterize the group of RA patients without erosions and identify its clinical predictors. Methods. Our study was conducted within a prospective observational cohort of RA patients recruited from the outpatient practice of an academic medical centre. We studied patients with bilateral hand radiographs at cohort baseline and 2-year follow-up assessed with Sharp/van der Heijde scores (SHS). The primary outcome was erosion-free status at baseline and 2-year follow-up. We assessed baseline values of the following as potential correlates: age at RA onset, gender, RA duration, BMI, 28-joint DAS (DAS-28), CRP, anti-CCP status, tender and swollen joint counts, functional status [multidimensional HAQ (MDHAQ)], tobacco use and RA treatments. Variables with P ≤ 0.25 in the univariate analyses were assessed using backward selection in multivariable logistic regression models. Results. Of the 271 subjects included, 21% (n = 56) were considered erosion free. Forty-six per cent (n = 26) of this group was anti-CCP positive compared with 56% (n = 121) in subjects with erosions present. Mean RA duration for erosion-free subjects was 3.9 years compared with 4.6 years in erosive subjects. Treatments for RA did not differ between the two groups. In the multivariable-adjusted analysis, significant predictors of erosion-free status were younger age at onset and shorter RA duration. Conclusion. In our cohort, 21% of subjects were erosion free at baseline and 2 years. Few baseline clinical characteristics significantly predicted erosion-free status.