Preoperative Neutrophil to Lymphocyte Ratio in Ulcerative Colitis is Associated with Denovo Crohn’s Disease after Ileal Pouch-Anal Anastomosis

BACKGROUND: About 5% to 10% of patients undergoing ileal pouch-anal anastomosis (IPAA) with a diagnosis of ulcerative colitis (UC) at the time of surgery are subsequently diagnosed with denovo Crohn’s disease (CD). Previous studies have shown that the neutrophil to lymphocyte ratio (NLR) has high sensitivity, specificity, and predictive values to differentiate CD patients from non-CD controls. The aim of this study was to examine the association of preoperative NLR and denovo CD after IPAA.

METHODS: Consecutive UC patients undergoing IPAA by one surgeon at a tertiary referral center were prospectively enrolled into a longitudinally updated database. Demographic and clinical factors were tabulated immediately after surgery. Preoperative NLR was collected and calculated from their CBC drawn up to 2 weeks before surgery, without knowledge of the patient’s surgical outcome. A cutoff of 1.65, from a previously published study (Forget et al., BMC Research Notes 2017) was used as the reference value. Denovo CD was defined by inflammation involving the small-bowel mucosa proximal to the ileal pouch or when a pouch fistula or other perianal complications developed more than 3 months after ileostomy closure.
 

RESULTS: The study cohort of 264 patients had a median age of 42 (5-79) years and included 139 (53%) males. Forty-four patients (17%) developed denovo CD on the basis of afferent limb inflammation (n=30), perianal disease (n=8), or both (n=6). Median length of time to denovo CD until final diagnosis was 9 months after stoma closure. Median NLR of the study cohort was 3.58 (0-54.3). Preoperative clinical features were similar between patients who had a normal (n=39;15%) or elevated NLR (n=225;85%). Denovo CD developed in 42 patients (19%) with an elevated NLR compared to only 2 patients (5%) with a normal NLR (p=0.03).

CONCLUSION(S): This first ever study examining the value of preoperative NLR and surgical outcomes after IPAA showed a significant association of preoperative NLR and denovo CD. An elevated preoperative NLR may be a relatively easy and low-cost clinical biomarker for the development of denovo CD following IPAA in UC patients.