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

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.