Time lag between active joint inflammation and radiological progression in patients with early rheumatoid arthritis

Objective. To determine clinical variables useful in predicting the prognosis of patients with early rheumatoid arthritis (RA) by investigating the relationship between clinical variables and radiological progression. Methods. One hundred eighteen patients with early RA whose symptoms developed within the previous year were enrolled in a prospective study. Data from the 98 patients who completed the 2 year study were analyzed, using the number of erosive joints and Larsen's score as the outcome of RA. Results. Increases in the number of erosive joints at 12 months after entry into the study were significantly correlated with the number of swollen joints (r = 0.510), erythrocyte sedimentation rate (ESR) (r = 0.404), and C-reactive protein (CRP) (r = 0.487) at 6 months. The same results were seen using Larsen's score as the measure of outcome. The average number of erosive joints or mean Larsen's score at 12 months was higher in patients whose levels of CRP were high at 6 months and suppressed by 12 months, but increased much less in patients whose levels of CRP were successfully suppressed by 6 months. More joint erosions were noted in patients with positive rheumatoid factor (RF) than in RF negative patients. Conclusion. Joint erosions appeared with a certain time lag after active synovitis. Earlier introduction of effective treatment is recommended for the prevention of RA joint damage. The presence of RF, number of swollen joints, ESR, and levels of CRP at 6 months after starting therapy are the most useful variables to predict radiological progression in patients with early RA.