Correlation of single time-point damage scores with observed progression of radiographic damage during the first 6 years of rheumatoid arthritis

Objective. Aggressive treatment of early rheumatoid arthritis (RA) is recommended to prevent irreversible joint damage. We evaluated the usefulness of single time-point joint radiographs for deciding whether early RA is erosive or nonerosive. Methods. In an observational study, 179 patients with recent onset of RA symptoms (median 5:1. mo), positive rheumatoid factor, and active polyarthritis had 2 to 8 radiographic observations of hands, wrists, and forefeet during 6 to 60 months of followup. Linear regression lines for all available radiographs were used to determine progression rates of total Sharp score (TSS), erosion score (ES), and joint space narrowing score (JSNS) of each patient. Results. Using the average of 2 readers',scores, intraclass correlation coefficient was 0.97 and smallest detectable difference was 3.07 for ES, 0.93 and 7.52 for JSNS, and 0.90 and 12.71 for TSS. Mean progression rates per year were 1.20 (ES); 0.67 (JSNS), and 1.85 (TSS). Single time-point radiographs taken within 6 months of symptom onset did not correlate with progression rates (r = 0.01 to 0.07); between 7 and 18 months correlations were weak (r = 0.23 to 0.35), but were better for ES between 19 and 72 months (r = 0.60 to 0.81). Among 53 patients (31%) with no progression of TSS, only 10 of them had zero scores at baseline. Among all 630 radiographs with TSS greater than or equal to 1, 25% were associated with progression rates less than or equal to 0. Conclusion. Erosion scores of single radiographic examinations done > 18 months after onset of RA symptoms correlated with progression rates, but earlier radiographs did not sufficiently predict erosive or nonerosive status to guide disease modifying antirheumatic drug treatment decisions.