Supplementary Material for: Fecal Lactoferrin Predicts Primary Nonresponse to Biologic Agents in Inflammatory Bowel Disease

<b><i>Introduction:</i></b> Fecal lactoferrin (FL) is a timely and accurate marker of inflammation in ulcerative colitis (UC) and Crohn’s disease (CD). The aim of this study was to verify whether FL can predict primary nonresponse (PNR) to biologic agents during induction. <b><i>Methods:</i></b> Retrospective outcome review in 27 patients (13 with CD and 14 with UC) tested for baseline FL and retested within a week after the first and second induction doses. Clinical/biochemical outcomes were evaluated at end of induction and at follow-up (3–24 months). <b><i>Results:</i></b> Compared to baseline, changes of the Harvey-Bradshaw (CD) and Partial Mayo Scoring (UC) indices at end of induction separated responders (18/27 or 67%) from nonresponders (9/17 or 33%). In all patients, the initial FL value at induction decreased compared to baseline, continuing to decrease after the following dose in clinical responders while bouncing back in the others. Models targeting the 2 consecutively decreased FL values or the second FL value compared to baseline or the second FL value compared to the first were able to accurately predict response at end of induction. Follow-up assessment confirmed clinical remission in initial responders (with FL values reduced on the average by 94 ± 10% compared to baseline). <b><i>Conclusions:</i></b> In CD and UC patients during induction with biologic agents, early FL measurements accurately separate clinical responders from those experiencing PNR. The method described here offers several potential advantages over other strategies to assess and manage these patients.