The acute phase and function in early rheumatoid arthritis. C-reactive protein levels correlate with functional outcome.
OBJECTIVE: To discover whether normalization of C-reactive protein (CRP) in patients with rheumatoid arthritis (RA) results in stabilization of their functional state, and whether a measure of disease activity can be used as a predictor of functional outcome. To examine the relationship between change of CRP and Health Assessment Questionnaire (HAQ) over a 24 mo period to define the sensitivity of HAQ to change. METHODS: A prospective study of 109 consecutive patients who fulfilled the American College of Rheumatology criteria for RA and had elevated CRP before steroid or 2nd line therapy. A full clinical assessment including HAQ was performed at presentation and at 3, 6, 12, and 24 mo. On the basis of the change in CRP at 6 mo, patients were divided into 3 groups: (1) CRP suppression to normal, (2) 50% reduction in CRP, and (3) less than 50% CRP change. RESULTS: The 3 groups were clinically and immunologically similar at onset. At 6 mo the median HAQ fell to 5 (lower to upper quartiles 7.5 to 19) in Group 1 (CRP normalized, n = 34), 6 (3.75 to 10) in Group 2 (CRP reduced by 50%, n = 30), and 12 (6 to 18) in Group 3 (less than 50% CRP change, n = 44), p < 0.005 for Groups 1 and 2 versus Group 3. At 12 and 24 mo HAQ remained significantly lower in Groups 1 and 2 compared with Group 3. In Group 1, patients either maintained a normal CRP (n = 28) or their CRP became elevated (n = 6). Only in those patients in whom a re-elevation of the CRP occurred was deterioration in HAQ subsequently seen. CONCLUSION: Suppression of elevated CRP in patients with active RA is associated with improvement in functional score, whereas persistent elevation of CRP is associated with functional deterioration. Once abnormal CRP is suppressed, no functional deterioration is likely to occur without re-elevation in CRP. Therefore, elevated CRP provides a convenient short term correlation with functional outcome and can be used as a guide for therapy. A HAQ score is a sensitive indicator of change in early disease.