PWE-260 Optimal C reactive protein cut-off point for predicting hospitalisation in patients with moderately active Crohn's disease
Authors: J-F Colombel, W J Sandborn, E Louis, R Panaccione, R B Thakkar, M M Castillo, M Yang, T Finney-Hayward, J Chao, P M Mulani
Journal: Gut (2012)

<h3>Introduction</h3> To identify high risk patients among patients with moderate Crohn9s disease (CD), we explored the association between C reactive protein (CRP) concentration and hospitalisation risk for patients with moderately active CD and identified the optimal CRP cut-off point as a marker to predict CD-related hospitalisation. CRP is a well-studied and commonly used laboratory marker of inflammation in CD.<sup>1</sup> The relationship between CRP and hospitalisation risk given the same Crohn9s Disease Activity Impairment (CDAI) score in patients with moderate CD has not been studied. <h3>Methods</h3> Data from CHARM, a 56-week (wk), randomised, placebo-controlled trial of adalimumab maintenance therapy, were analysed. All patients received adalimumab during a 4-wk, open-label induction period; patients were then randomised to adalimumab or placebo for a 52-wk double-blind period. For this analysis, only patients who were randomised to placebo at Wk 4 and had moderate CD, defined as CDAI ≤300 at Wk 4, were analysed. A Cox model was applied to analyse the association between Wk-4 CRP concentration and the probability of having a CD-related hospitalisation during the 52-wk double-blind period. Wk-4 CDAI score, Wk-4 steroid use, age, sex, weight, body mass index, and prior anti–tumour necrosis factor use were also adjusted in the model. Patients were censored if they switched to open-label adalimumab or dropped out. A receiver operating characteristic (ROC) curve was used to identify the optimal CRP cut-off point to best predict the 52-wk CD-related hospitalisation rate. <h3>Results</h3> The analysis population included 214 patients randomised to placebo with Wk-4 CDAI ≤300. An elevated Wk-4 CRP concentration was associated with a greater chance of CD-related hospitalisation (HR=1.24; p=0.002). The ROC curve identified a CRP concentration =1.41 mg/dl as the dichotomising point (area under the curve=0.68; sensitivity=0.58; specificity=0.80). Risk of CD-related hospitalisation during the double-blind period was 3.4 times greater for patients with CRP concentrations ≥1.41 mg/dl at Wk 4 vs patients with CRP concentrations &lt;1.41 mg/dl (p=0.015), with control for CDAI and other covariates. <h3>Conclusion</h3> Early CRP concentration represents a moderate to good marker to predict CD-related hospitalisation for patients with moderately active CD given the same CDAI score. CRP concentration of 1.41 mg/dl was the optimal cut-off point for predicting long-term CD-related hospitalisation. <h3>Competing interests</h3> J-F Colombel Consultant for: Abbott, Speaker bureau with: Abbott, W Sandborn Grant/Research Support from: Abbott, Consultant for: Abbott, E Louis Speaker bureau with: Abbott, Conflict with: Abbott, R Panaccione Grant/Research Support from: Abbott, Consultant for: Abbott, Speaker bureau with: Abbott, Conflict with: Abbott, R Thakkar Shareholder with: Abbott, Employee of: Abbott, M Castillo Shareholder with: Abbott, Employee of: Abbott, M Yang Shareholder with: Abbott, Employee of: Abbott, T Finney-Hayward Shareholder with: Abbott, Employee of: Abbott, J Chao Shareholder with: Abbott, Employee of: Abbott, P Mulani Shareholder with: Abbott, Employee of: Abbott. <h3>Reference</h3> 1. <b>Henriksen M</b>, <i>et al</i>. <i>Gut</i> 2008;<b>57</b>:1518–23.