EP334 - Conversion Rate Of Ulcerative Colitis to Crohn's In Patients With An IPAA

Purpose/Background: Surgical management of Ulcerative Colitis (UC) may include total proctocolectomy with ileal pouch anal anastomosis (IPAA). The role of IPAA in Crohn's Disease (CD) remains controversial. Conversion of diagnosis of UC to CD after IPAA has been described with estimated rate of 10% [2]. This retrospective study uses the TriNetX global database, which includes over 190 million de-identified patients, to study the conversion rate of UC to CD in patients with an ileal pouch.

Methods/Interventions: To examine the rate of CD conversion, we constructed patient cohorts to include all patients diagnosed with UC based on ICD-10 codes, that underwent open or laparoscopic proctectomy IPAA as reported by CPT codes. We then determined the rate of conversion to CD after IPAA by querying the database for patients who subsequently received a diagnosis of CD within 10, 12 and 15 years of surgery. To compare baseline patient characteristics between those with and without a CD diagnosis, we used propensity score matching for age, sex, and race to compare rates of obesity, diabetes mellitus (DM), and smoking status.

Results/Outcomes: The cohort had a total of 1,805 patients who were diagnosed with UC and underwent IPAA. 1,321 patients were included for analysis, while 475 were excluded due to CD diagnosis prior to IPAA. The rate of conversion to CD within this cohort at 10, 12, and 15 years was 18.1%, 18.2%, and 18.7%, respectively. Comparing rates of baseline characteristics after propensity score matching for age, sex, and race between patients with and without a CD diagnosis did not show any significant differences in obesity, DM, or smoking history (p=0.55, 0.18, 0.13 respectively). Results are summarized in Table 1.

Conclusion/Discussion: In this study, the rate of CD diagnosis in patients with UC that underwent IPAA was at least 18% at all included time points, which is higher than the current literature suggests. This study represents the largest patient sample studied in regards for IPAA conversion to CD. This study is limited by its retrospective nature and its basis on administrative data. While our data suggests that the rate of conversion to diagnosis of CD may be higher than previously reported, high quality prospective data is needed to further validate this as well as identify patient characteristics and other potential factors contributing to the conversion of UC to CD. This potential complication remains an important part of consent for a patient with UC undergoing IPAA.

Table 1: UC to Crohn's Conversion Rate and Patient Characteristics