Neutrophil-to-lymphocyte ratio for predicting postoperative recurrence in Crohn’s disease patients with isolated anastomotic lesions

**Background:** Crohn's disease (CD) is a chronic relapsing inflammatory condition; over 50% of patients require intestinal resection. The Rutgeerts score predicts postoperative prognosis, but patients with isolated anastomotic lesions (iAL, modified Rutgeerts score i2a) have heterogeneous outcomes. The neutrophil-to-lymphocyte ratio (NLR) is a non-invasive biomarker reflecting disease activity in inflammatory diseases, but its prognostic value in CD patients with iAL was unknown.

**Methods:** This bicenter retrospective cohort study recruited CD patients who underwent elective ileocolonic resection at two hospitals (First Affiliated Hospital and Sixth Affiliated Hospital of Sun Yat-sen University) from January 2013 to December 2020. Inclusion criteria: CD diagnosis, initial postoperative endoscopy showing iAL (i2a), NLR available within 1 week of endoscopy, and ≥3 months follow-up. Exclusion criteria: postoperative infection or concurrent autoimmune diseases. The primary outcome was clinical recurrence (hospitalization for exacerbation, medication escalation, re-operation, or endoscopic recurrence). Secondary outcome was endoscopic recurrence (modified Rutgeerts score ≥ i2b). Optimal NLR cutoff was determined by X-tile software. Kaplan–Meier curves, log-rank tests, and Cox proportional hazards regression were used.

**Key Results:** Of 411 patients reviewed, 83 were eligible (60 male, 72.3%; median age at surgery 30.8 years; median follow-up 14.9 months). 36 patients (48.6%) experienced clinical recurrence over a median 16.3 months. NLR > 2.45 (cutoff determined by X-tile) and age at surgery >45 years were significantly associated with shorter clinical recurrence-free survival on Kaplan–Meier analysis. After adjusting for surgery history and medications, NLR > 2.45 was the only independent risk factor for clinical recurrence (adjusted HR 2.88, 95% CI 1.39–6.00, p = 0.005). For endoscopic recurrence (68 patients analyzed), NLR > 2.45 had an adjusted HR of 4.54 (95% CI 1.07–19.3, p = 0.040). A risk score (0–2) based on NLR > 2.45 and age at surgery >45 years showed graded risk: score 1 had adjusted HR 2.48 (95% CI 1.22–5.02) for clinical recurrence; score 2 had adjusted HR 6.97 (95% CI 2.19–22.16, p = 0.001). Median clinical recurrence-free survival was 34.1, 17.9, and 7.7 months for scores 0, 1, and 2, respectively.

**Clinical Implications:** NLR is a readily available, non-invasive biomarker that independently predicts postoperative recurrence in CD patients with iAL. The simple risk score combining NLR and age at surgery may help clinicians stratify patients for personalized postoperative management, including more aggressive prophylaxis for high-risk patients. Limitations include retrospective design, relatively small sample size (especially for score 2, n=6), lack of fecal calprotectin data, and wide confidence intervals for some estimates. Prospective validation in larger cohorts is needed.