INDIVIDUAL RELATIONSHIP BETWEEN PROGRESSION OF RADIOLOGICAL DAMAGE AND THE ACUTE-PHASE RESPONSE IN EARLY RHEUMATOID-ARTHRITIS - TOWARDS DEVELOPMENT OF A DECISION-SUPPORT SYSTEM

Objective. Evaluation of the individual relationship between C-reactiv e protein (CRP) production or erythrocyte sedimentation rate (ESR) and progression of radiologic damage in early rheumatoid arthritis (RA), to improve the predictive value of monitoring the acute phase response . Methods, The relationship was modeled mathematically using adjustmen ts for discontinuity in the radiographic scoring system and for cluste ring in the occurrence of score points in the initial phase. The model was evaluated in a prospective study of 149 patients with early RA, m onthly CRP assays, and 6-monthly Sharp scores of radiographs of the ha nds and fret. Results, Time integrated CRP values correlated closely w ith radiologic progression in each patient, but there was considerable variation between individuals with similar radiographic scores. The t heoretical model accommodated these results, and based on CRP measurem ents and radiographic scores over 6 months, it provided a k value for each patient that reflected the individual relationship between CRP an d radiologic damage. Using this k value combined with actual CRP level s over 3 and 6 years, the model accurately predicted the extent of rad iologic progression that was actually observed at these times, Best re sults were obtained using estimation of the k value from 6 or 12 month observational data. The model has been incorporated into a software p rogram for routine clinical use that indicates the levels to which CRP should fall to prevent further joint damage, Similar results were obt ained for ESR, Conclusion, A model has been established defining the i ndividual relationship between time integrated CRP and ESR values, ref lecting rheumatoid disease activity, and progression of radiologic dam age. It accurately predicts outcome from 6 months after presentation a nd can be used as a practical decision support system.