C-Reactive protein reduction rate following initiation of anti-tumor necrosis factor α induction therapy predicts secondary loss of response in patients with Crohn's disease.

The objective of this study is to identify clinical predictors of primary non-response (PNR) and secondary loss of response (LOR), in Crohn's disease (CD) patients treated with anti-tumor necrosis factor α (anti-TNF) agents. This retrospective, longitudinal, and observational cohort study included 283 patients with CD who received anti-TNF treatments from November 2006 to July 2017 at Samsung Medical Center, Seoul, Korea. A total of 212 patients with CD were eligible and based on clinical responses, divided into three groups: PNR, LOR, and responder groups. PNR occurred in 13 patients (6.1%). C-Reactive protein (CRP) level at initiation of anti-TNF (baseline CRP) was a possible predictor of PNR compared to the non-PNR group (baseline CRP >1 mg/dl, OR = 4.34, 95% CI = 1.06-17.83,   .042). During maintenance therapy, incidence of LOR was 12.2% at 1-year, 23.6% at 2-years, 36.3% at 3-years, and 52.1% at 5-years. Combining baseline CRP level and CRP reduction rate [(CRP at 12-14 weeks-baseline CRP)/baseline CRP] was a possible predictor of 1-year LOR compared to the responder group (baseline CRP >1 mg/dl and CRP reduction rate > -70%, OR = 18.86, 95% CI = 3.40-104.55,   .001). In the Cox hazard proportional model, a combination of baseline CRP level and CRP reduction rate was possible predictors of long-term LOR during maintenance therapy (baseline CRP >1 mg/dl and CRP reduction rate > -70%, HR = 5.84, 95% CI = 2.75-12.41,   .001). Baseline CRP level and CRP reduction rate might be clinical predictors for PNR or LOR to anti-TNF in patients with CD, and could guide proper therapeutic interventions in patients with CD.