To determine the development rate of erosions and joint space narrowing in a cohort of patients during the first 3 years of rheumatoid arthritis (RA).
All consecutive patients fulfilling the American Rheumatism Association criteria and seen within the 1st year of the disease were followed prospectively with biannual radiographs of hands and feet. One hundred and forty-seven patients were followed for 2 years and 90 patients for 3 years. Erosions and joint space narrowing were scored with a modified version of Sharp's method (van der Heijde modification). Wilcoxon's rank sum test was used to test differences between joints and between erosions and joint space narrowing.
On average, at 3 year followup most groups of joints showed about 8% of the maximum possible score. In most groups of joints about 20% of the joints were affected. At the start more foot joints were affected than hand joints. However, the increase in the number of affected joints and in the radiographic damage was similar in hands and feet. Consequently, the predominance of affected foot joints was still present after 3 years. The progression in the 3rd year was statistically significantly less compared to the 1st year. This was more pronounced for the number of affected joints than for radiographic damage.
We found that 70% of the patients showed radiographic damage after 3 years and this group could already be selected after 1 year. Overall, +/- 18-20% of the joints were affected after 3 years, with relatively few abnormalities per joint (+/- 8% of the maximum possible score was reached). The rate of progression in the 1st year was significantly more than in the 2nd and 3rd years, indicating a flattening of the curve of radiographic progression.