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Arthritis Rheum. 2005 Jan;52(1):42-8.

C-reactive protein as a predictor of infliximab treatment outcome in patients with rheumatoid arthritis: defining subtypes of nonresponse and subsequent response to etanercept.

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1
University of Leeds, Leeds General Infirmary, Great George Street, Leeds LS1 3EX, UK.

Abstract

OBJECTIVE:

Nonresponse to anti-tumor necrosis factor alpha in patients with rheumatoid arthritis (RA) is poorly understood. The aims of this study were to define nonresponse patterns using infliximab and C-reactive protein (CRP) profiles, to assess the predictive power of a CRP response for outcome, and to correlate these findings with subsequent response to etanercept.

METHODS:

We studied 207 patients with resistant RA who were started on treatment with infliximab. After 12 weeks, the American College of Rheumatology 20% improvement criteria (ACR20) were used to classify patients as responders (ACR20 response or greater) or nonresponders (NRs). The NRs were further subdivided into 3 groups according to the CRP response at weeks 2, 6, and 12. Within the NR group, those with a suppressed CRP at week 12 continued taking infliximab for a further 12 weeks; those without a CRP response were switched to etanercept, and the ACR response at 12 weeks was calculated.

RESULTS:

At week 12, 54% of patients achieved an ACR20 response, and 46% failed to achieve a response. Of the NRs, 63% demonstrated a significant reduction in the CRP level at week 12, 59% of whom achieved an ACR20 response at week 24 on continuation of infliximab. Of the patients who did not demonstrate a significant reduction in the CRP level after the first infusion, 86% failed to show a biochemical or ACR20 response by week 12. Twenty-four percent of the NRs had a temporary reduction in the CRP level, and 13% of the NRs showed no CRP reduction. Seventy-five percent of these NRs switched to etanercept, and 68% of this group achieved an ACR20 response at week 12 (51% achieved an ACR50 response), with a CRP response in 63%.

CONCLUSION:

Infliximab NRs comprise subtypes with distinct CRP patterns. Failure to suppress the CRP at week 2 identified the majority of patients who were NRs at week 12. CRP suppression at week 12 in the NRs was associated with a late clinical improvement with infliximab treatment (24 weeks), whereas failure to suppress the CRP at week 12 was associated with a good response on switching to etanercept.

PMID:
15641046
DOI:
10.1002/art.20711
[Indexed for MEDLINE]
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