Relationship between time-integrated disease activity estimated by DAS28-CRP and radiographic progression of anatomical damage in patients with early rheumatoid arthritis

BACKGROUND The main aim of the study was to investigate the relationship between persistent disease activity and radiographic progression of joint damage in early rheumatoid arthritis (ERA). METHODS Forty-eight patients with active ERA was assessed every 3 months for disease activity for 3 years. Radiographic damage was measured by the Sharp/van der Heijde method (SHS). The cumulative inflammatory burden was estimated by the time-integrated values (area under the curve-AUC) of Disease Activity Score 28 joint based on C-reactive protein (DAS28-CRP) in rapid progressors versus non-progressors. Bland and Altman's 95% limits of agreement method were used to estimate the smallest detectable difference (SDD) of radiographic progression. The relationship between clinical and laboratory predictors of radiographic progression and their interactions with time was analysed by logistic regression model. RESULTS After 3-years of follow-up, radiographic progression was observed in 54.2% (95%CI: 39.8% to 67.5%) of patients and SDD was 9.5 for total SHS. The percentage of patients with erosive disease increased from 33.3% at baseline to 76% at 36 months. The total SHS of the progressors worsened from a median (interquartile range) of 18.5 (15-20) at baseline to 38.5 (34-42) after 3 years (p < 0.0001) whereas non-progressors worsened from a median of 14.5 (13-20) at baseline to 22.5 (20-30) after 3 years (p < 0.001). In the regression model, time-integrated values of DAS28-CRP and anti-CCP positivity have the highest positive predictive value for progression (both at level of p < 0.0001). Radiographic progression was also predicted by a positive IgM-RF (p0.0009), and a high baseline joint damage (p = 0.0044). CONCLUSIONS These data indicate that the level of disease activity, as measured by time-integrated DAS28-CRP, anti-CCP and IgM-RF positivity and a high baseline joint damage, affects subsequent progression of radiographic damage in ERA.