Amy L Hamilton, Michael A Kamm, Peter De Cruz, Emily K Wright, Fabiyola Selvaraj, Fred Princen, Alexandra Gorelik, Danny Liew, Ian C Lawrance, Jane M Andrews, Peter A Bampton, Miles P Sparrow, Timothy H Florin, Peter R Gibson, Henry Debinski, Richard B Gearry, Finlay A Macrae, Rupert W Leong, Ian Kronborg, Graham Radford‐Smith, Warwick Selby, Sally J Bell, Steven J Brown, William R Connell

Disease recurs frequently after Crohn's disease resection. The role of serological antimicrobial antibodies in predicting recurrence or as a marker of recurrence has not been well defined. 169 patients (523 samples) were prospectively studied, with testing peri-operatively, and 6, 12 and 18 months post-operatively. Colonoscopy was performed at 18 months post-operatively. Serologic antibody presence (pANCA, ASCA IgA/IgG, anti-OmpC, anti-CBir1, anti-A4-Fla2, anti-Fla-X) and titre were tested. Quartile sum score (range 6-24), logistic regression analysis, and correlation with phenotype, smoking status and endoscopic outcome were assessed. Patients with ≥2 previous resections were more likely to be anti-OmpC positive (94% vs. 55%, ≥2 v <2, P = 0.001). Recurrence at 18 months was associated with anti-Fla-X positivity at baseline (49% v 29%; positive v negative, P = 0.033) and 12 months (52% v 31%, P = 0.04). Patients positive (n = 28) for all four antibacterial antibodies (anti-CBir1, anti-OmpC, anti-A4-Fla2 and anti-Fla-X) at baseline were more likely to experience recurrence at 18 months than patients negative (n = 32) for all four antibodies (82% v 18%, P = 0.034; OR 6.4, 95% CI 1.16-34.9). The baseline quartile sum score for all six antimicrobial antibodies was higher in patients with severe recurrence (Rutgeert's i3-i4) at 18 months, adjusted for clinical risk factors (OR 1.16, 95% CI 1.01-1.34, P = 0.039). Smoking affected antibody status. Anti-Fla-X and presence of all anti-bacterial antibodies identifies patients at higher risk of early post-operative Crohn's disease recurrence. Serologic screening pre-operatively may help identify patients at increased risk of recurrence.