Fibrosis Scores in Inflammatory Bowel Disease Patients With a History of Ileostomy or Ileal Pouch Surgery With Exposure to Methotrexate and Thiopurines

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Introduction: Given the risk of developing liver fibrosis, liver societies recommend periodic monitoring of AST, ALT, and albumin levels in patients on methotrexate (MTX) and thiopurines (TP). One previous study documented a rate of severe fibrosis in 5 of 124 CD patients on MTX. The aim of our study was to evaluate the prevalence of liver fibrosis in MTX and/or TP treated IBD patients who have a history of an ileostomy or pouch surgery using various non- invasive techniques including transient elastography, fibrosis biomarkers and fibrosis scores.

Methods: Patients seen in the IBD Center at Boston Medical Center with a history of an ileostomy or ileal pouch surgery were approached to participate in this IRB approved study. At entry, enrolled patients underwent vibration-controlled transient elastography. The AST to Platelet Ratio Index (APRI) and Fibrosis-4 (FIB-4) were calculated.

Results: A total of 32 patients, 9 (28%) with ulcerative colitis (UC), 21 (66%) with Crohn's disease (CD) and 2 (6%) with indeterminate colitis were enrolled in the study from 8/16 to 5/18. The average age was 46 years old and 56% were female. The average BMI was 27.6 m/kg². Five (16%) patients were noted to have a liver stiffness measurement > 7.1 kPa (Table 1). One patient in the unexposed group had an F2> 2 (10%) and four patients in the in MTX/TP group (18%) had an F2> 2 (p=0.55). The one patient in the unexposed group was noted to have a prior history of NAFLD whereas none of the four patients in the MTX/TP group had a prior history of underlying liver disease (Table 2). One patient in the MTX/TP group had a FIB-4 > 3.25 with no patients in the unexposed group with an elevated FIB-4. Neither patients in the MTX/TP nor the unexposed groups were noted to have an APRI > 1.0.

Conclusion: In this study of IBD patients with a history of an ileostomy or ileal pouch surgery, 16% had an elastography score > 7.1kDa. The rate was not increased in patients on MTX/TP. There appears to be a low rate of significant liver injury in this subset of patients. We plan further follow-up of this cohort to identify patients with evidence of progressive liver disease in an effort to determine if the use of noninvasive techniques can identify those at risk for advanced liver injury.

639_A Figure 1. Baseline characteristics of patients with UC vs CD vs indeterminate colitis.

639_B Figure 2. Baseline characteristics of patients in the exposed vs unexposed groups.