Comparative Value of CRP and FCP for Endoscopic and Histologic Remissions in Ulcerative Colitis

Abstract

Aim: We have previously shown that CRP < 2.9 mg/L is a better predictor of endoscopic remission (ER) than CRP < 5 mg/L in ulcerative colitis (UC). Here, we prospectively evaluate CRP and FCP cut-offs and compare them in predicting ER and histological remission (HR) in UC. Method: One hundred thirty-five steroid-free UC patients were evaluated prospectively. ER was defined as Mayo endoscopic sub-score 0-1. In colonoscopy, the colon was evaluated as seven segments: rectum, sigmoid, descending, proximal-transverse, distal-transverse, ascending colon, and cecum. Two biopsies of each segment were evaluated for histological inflammation and graded using the Nancy and Geboes scores. All segment biopsies with Nancy < 1 and Geboes < 2 were defined as HR. Results: The optimum cut-off values for FCP and CRP were 120 μg/g and 2.75 mg/L for ER, respectively. AUC values of FCP and CRP were similar for ER and Mayo-0 disease in ROC analysis. CRP and FCP also had similar performances with these cut-offs regarding ER. While CRP was a predictor to assess the extensiveness of active UC, FCP was not. ROC analysis showed no difference between CRP and FCP regarding HR. Cut-off values for HR were 2.1 mg/L and 55 μg/g for CRP and FCP, respectively. CRP and FCP, in combination with the mentioned cut-off values, detected ER and HR in nearly 2/3 and ½ of the patients, respectively, with high specificity. Conclusions: Reappraised CRP (ER: 2.75 mg/L, HR: 2.1 mg/L) has as much diagnostic contribution as relevant FCP in predicting ER and HR and contributes more to revealing the proximal extension in active colitis compared to FCP. Relevant CRP and FCP combinations may improve the prediction rates.

Keywords: CRP; histological remission; ulcerative colitis.

Figure 1

Participant flow diagram. One hundred sixty-two patients were screened and 135 were enrolled to study. Endoscopic remission (ER) and histologic remission (HR) were evaluated. CRP and FCP cut-off were determined, and their performances were compared in predicting ER and HR.

Figure 2

Receiver operating characteristics (ROC) curve analyses of CRP and FCP in predicting endoscopic remission (Mayo 0–1) and Mayo-0 disease. The AUC for CRP was 0.784 (confidence interval: 0.70–0.86), and the AUC for FCP was 0.849 (CI: 0.77–0.92) in endoscopic remission. The AUC for CRP was 0.718 (CI: 0.63–0.80), and the AUC for FCP was 0.816 (CI: 0.83–0.89) in Mayo-0 disease. There was no statistically significant difference between the AUC values of CRP and FCP for endoscopic remission (p: 0.169) and Mayo-0 disease (p: 0.09).

Figure 3

Receiver operating characteristics (ROC) curve analyses of CRP and FCP regarding HR prediction. AUC values were calculated as 0.767 (CI: 0.66–0.87) for CRP and 0.797 (CI: 0.70–0.89) for FCP. The difference between CRP and FCP’s AUC values was not significant (p: 0.62).

Figure 4

Comparison of patients with proctitis and extensive colitis in terms of CRP and FCP. In the proctitis group, the median CRP was 4.6 mg/L (IQR: 4.1), and the median FCP was 333 μg/mg (IQR: 892); in the extensive colitis group, the median CRP was 12 mg/L (IQR: 15.3), and the median FKP was 831 μg/mg (IQR: 990). The difference between the CRP values of proctitis and extensive colitis was significant (p: 0.04). The difference between the FCP values of proctitis and extensive colitis was insignificant (p: 0.220).