Risk of Myeloproliferative Neoplasms in Patients With Inflammatory Bowel Disease and Impact on Outcomes: A Multi‐Centre Matched Analysis

BACKGROUND: Inflammatory bowel disease (IBD) and myeloproliferative neoplasms (MPNs) share chronic inflammation and immune dysregulation. AIM: We evaluated the incidence of MPNs among patients with IBD and clinical outcomes of IBD-MPN coexistence. METHODS: Two retrospective cohort analyses were conducted using the TriNetX database. First, adults with ulcerative colitis (UC) or Crohn's disease (CD) were compared with matched non-IBD controls to estimate incident MPN risk. A coexistence second analysis included patients with UC or CD who developed MPNs and then were matched to IBD without MPN controls to assess 5-year outcomes, including IBD-related complications, surgical interventions, colorectal cancer (CRC) and primary sclerosing cholangitis (PSC). Medication subgroup analyses were performed to evaluate associations with MPN risk. RESULTS: After matching, 3873 patients with UC-MPN and 3474 patients with CD-MPN were included. Compared with matched non-IBD controls, incident MPN risk was higher in UC (HR 1.60, p = 0.01) and CD (HR 1.56, p < 0.001). In CD, MPN coexistence was associated with higher risks of CRC (HR 1.52, p = 0.012), intestinal fistula (HR 2.84, p < 0.001), obstruction (HR 2.05, p < 0.001), perforation (HR 2.37, p < 0.001), small bowel resection (HR 3.69, p < 0.001) and colectomy (HR 2.10, p < 0.001). In UC, MPN coexistence was associated with higher risks of CRC (HR 1.50, p = 0.001), PSC (HR 1.75, p = 0.03) and pouchitis (HR 1.68, p = 0.003). Exposure to thiopurines (HR 1.28, p < 0.001) was associated with increased MPN risk, whereas TNF, IL-23 and JAK inhibitors were not. CONCLUSIONS: IBD is associated with increased MPN risk, and IBD-MPNs coexistence is associated with worse IBD-related complications and malignancy risk.