Background: Despite the use of anti-TNF therapy for prevention of postoperative recurrence, more than 20% of Crohn's disease (CD) patients present an endoscopic recurrence 6 months after surgery. The aim of our study was to assess the relationship between serum adalimumab (ADA) concentration 3 months after surgery and endoscopic recurrence at 6 months in CD patients treated with adalimumab for prevention of postoperative recurrence.
Methods: This was a prospective, multicenter study between January 2014 and March 2016. All CD patients who underwent an ileocecal resection with ileocolonic anastomosis and were treated with ADA monotherapy (introduced one month after surgery subcutaneously with 160 mg at week 0, 80 mg at week 2 and then 40 mg every week), for prevention of postoperative recurrence were included in the study. Serum ADA concentration was determined 2 months after ADA introduction. Endoscopic recurrence at 6 months was defined as a Rutgeerts endoscopic score ≥ i2.
Results: Fifteen CD patients were included (9 male and 6 female), with a median age of 24 years-old [15–47]. Disease phenotype was considered as penetrating in 8 patients (53%), stricturing in 5 patients (34%) and inflammatory in 2 (13%). Eight (53%) patients had an isolated ileal disease and 7 (47%) an ileocolonic location. Eight patients (53%) had at least 2 risk factors for postoperative recurrence according to ECCO guidelines and 14 (93%) were already treated with anti-TNF before surgery. The overall endoscopic recurrence rate was 46.7%. The median serum ADA concentration 3 months after surgery was 7.9 μg/mL (0.04–11.8) and no patient had anti-ADA antibodies. Median serum ADA concentration was significantly higher in CD patients without endoscopic postoperative recurrence compared to CD patients with endoscopic postoperative recurrence (8.2 μg/mL vs 2.5 μg/mL, p=0.121). According to Rutgeerts score, the median serum ADA concentration was 8.2, 5.1 and 0.2 mg/mL in patients with a score ≤ i1, i2 and ≥i3, respectively (p=0.033). Indeed, the serum ADA concentration was inversely correlated to the Rutgeerts score (Pearson coefficient = −0.61, p=0.015). The ROC curve analysis demonstrated a specificity of 71% and a sensitivity of 87% for serum ADA concentration threshold of 4 μg/mL to predict endoscopic recurrence (area under the curve = 0.75±0.14). Thus, 83% of CD patients with a serum ADA concentration <4 μg/mL had an endoscopic recurrence, compared to 22% of CD patients with a serum ADA concentration >4μg/mL (p=0.04).
Conclusions: In our study, there was a significant correlation between serum ADA concentration 3 months after surgery and endoscopic postoperative recurrence at 6 months in CD patients treated with ADA to prevent postoperative recurrence.