High C-reactive Protein in Crohn's Disease Patients Predicts Nonresponse to Infliximab Treatment

Background: Infliximab (IFX) is effective in treating Crohn's disease (CD) and C-reactive protein (CRP) is a useful biomarker in assessing inflammatory activity.

Aim: Correlate CRP levels before beginning of IFX, at week 14 and CRP delta within the first year of IFX treatment.

Methods: Retrospective study of CD patients undergoing treatment with IFX. Primary nonresponse (PNR) was defined as no symptomatic improvement and CRP persistently elevated; sustained response (SR) as symptomatic improvement for at least 1 year without therapeutic adjustment; response after therapeutic adjustment (RTA) as analytic and clinical response but requiring IFX dose/frequency adjustment or association with another drug.

Results: Baseline CRP levels were higher in PNR compared with SR (26.2mg/L vs 9.6 mg/L, p=0.015) and RTA (26.2mg/L vs 7.6 mg/L, p=0.007). CRP levels greater than 15 mg/L at baseline predict PNR with 67% sensitivity and 65% specificity. Lower CRP levels at week 14 were more likely to predict SR relative to RTA (3.1mg/L vs 7.6 mg/L p=0.019) and PNR (3.1mg/L vs 9.1mg/L; p=0.013). CRP levels greater than 4.6 mg/L at week 14 predict PNR with 67% sensitivity and 62% specificity. A higher CRP delta between beginning of treatment and week 14 is more likely to predict SR relative to RTA (5.2mg/L vs 0.6 mg/L p=0.027).

Conclusion: CRP levels at week 14 were associated with SR in patients treated with IFX, independently of baseline CRP serum levels. High inflammatory burden at beginning of IFX treatment was correlated with a worse response.