The level of inflammation in rheumatoid arthritis is determined early and remains stable over the longterm course of the illness.

OBJECTIVE: To determine whether the level of inflammatory activity, determined by the erythrocyte sedimentation rate (ESR), changes over the longitudinal course of rheumatoid arthritis (RA); whether the level of inflammatory activity identified early in RA predicts longterm inflammatory status; and whether RA "bums out" after many years of inflammatory activity.
METHODS: A total of 21,866 consecutive ESR determinations from 1,897 patients with RA were analyzed to determine the association of inflammatory activity, as estimated by ESR, with duration of disease. Data were modeled by generalized estimating equations and random selection fractional polynomial regression models, controlling for age, sex, and calendar date.
RESULTS: In a nonlinear fashion, ESR decreased by 4 mm/h over the first 10 years of disease, remained stable over the next 25 years, and increased slightly thereafter. Patients treated more recently had lower ESR values. Patients with recent onset of RA, when stratified in quartiles of ESR, maintained their position over time.
CONCLUSION: Although ESR decreases by 4 mm/h over the first 10 years of disease, it remains stable or rises thereafter. The course of RA, as modeled by the ESR, appears to be "set" early in the disease and good and bad prognosis groups can be identified within the first 2 years. There is no evidence of general "burned out" RA or a lessening of disease activity with long duration of disease. Our findings tend to suggest that the ("usually treated") natural history of RA prior to introduction of antitumor necrosis factor agents is toward some degree of improvement in the early years. If the newer and combination therapies are indeed substantially better than what has been available, they must show a shifting of the curve downward, not just in the early years where it has occurred historically, but over the entire course of the illness.