A192 EFFICACY OF USTEKINUMAB IN SMALL BOWEL STRICTURES OF FIBROSTENOTIC CROHN'S DISEASE AS ASSESSED BY INTESTINAL ULTRASOUND

Background

Small bowel Crohn’s disease (CD) strictures can lead to debilitating obstructive symptoms and the deterioration of quality of life. Imaging modalities such as intestinal ultrasound (IUS) are invaluable in the diagnosis of strictures. The use of IUS in CD is rapidly growing, is cost-effective, easily repeatable, and similar in accuracy to magnetic resonance enterography. Evidence for medical management of fibrostenotic CD has been limited to anti-tumor necrosis factor biologics. Studies on the efficacy of other biologic therapies for strictures such as ustekinumab, a p40/interleukin 12 and 23 inhibitor, are lacking.

Purpose

The objective of this study was to evaluate the efficacy of ustekinumab in the treatment of small bowel strictures on IUS.

Method

This retrospective cohort study evaluated the IUS changes of terminal ileal (TI) CD strictures at baseline and 12 months following ustekinumab initiation from 2016 to 2020 at a single tertiary care center. Strictures identified were defined as 1) increased bowel wall thickness (BWT) > 3mm, 2) narrowed luminal apposition, and 3) presence of pre-stenotic dilation (PSD) or the inability to pass the colonoscope through the narrowed area. Changes in sonographic parameters (BWT, luminal size, PSD, length, hyperemia, inflammatory fat, dysfunctional peristalsis) were recorded at baseline prior to initiation of ustekinumab and compared 12 months after treatment. Differences from baseline to 12 months were paired within-person and statistical analysis was performed using paired T-tests for continuous variables and McNemar’s test for categorical variables.

Result(s)

Of the 18 patients identified, 55% (n = 10) were male, median age was 49 years (Q1-Q3: 33-63 years) at initial scan, with median CD duration of 10 years (Q1-Q3: 8-20 years). The majority of TI strictures were surgically naïve (67%, n = 12). Between pre- and 12-month post ustekinumab therapy scans, there was significant improvement in BWT [8.2 mm vs 7.2 mm, p = 0.048], however there was no significant difference in the presence of peri-enteric inflammatory fat (p = 0.10), mean stricture length (17.7 vs 21.7 cm, p = 0.18), and mean stricture lumen diameter (3.3 mm vs 2.7 mm, p = 0.44) (Table 1). There was also no significant difference in the presence of stricture-associated peri-enteric fat (89% vs 67%, p = 0.10), stricture-associated hyperemia (83% vs 89%, p = 0.65) or dysfunctional peristalsis (50% vs 61%, p = 0.41) (Table 1).

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Conclusion(s)

Our study is the first to report the efficacy of ustekinumab in small bowel CD strictures using IUS at baseline and 12 months. This study shows that although ustekinumab leads to improvement in overall sonographic appearance of bowel thickness, it does not improve luminal narrowing nor PSD, two hallmark criteria of fibrostenosis. More extensive studies with larger sample sizes evaluating ustekinumab, or combination therapies, are required to identify their role in stricturing CD.

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Disclosure of Interest

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A107 VISCERAL ADIPOSE TISSUE VOLUME DIFFERENTIATES BETWEEN FIBROSTENOTIC AND INFLAMMATORY CROHN’S DISEASE

Background

Creeping fat, a form of visceral adipose tissue (VAT) that wraps the intestinal wall, influences the formation of Crohn’s disease (CD) strictures. The degree of fat wrapping from intestinal stricture resections is correlated with the extent of chronic inflammation, fibrosis, stricture formation, and response to biologic therapy. VAT and subcutaneous adipose tissue (SAT) ratios from CTE (computed tomography) scans are elevated in CD strictures. However, the definition of strictures in these studies has been poorly defined and not included current well-recognized criteria: 1) bowel wall thickness (BWT), 2) narrowed luminal diameter, and 3) pre-stenotic dilation. (PSD).

Purpose

The objective of this pilot study was to assess the relationship of 2D and 3D VAT:SAT ratios with CT stricture parameters in patients with terminal ileal (TI) CD strictures.

Method

2D VAT:SAT ratios from CT’s of CD patients with TI strictures defined as increased BWT, narrowed luminal diameter (< 50% relative to normal adjacent distended loop), and PSD greater than the stricture diameter were retrospectively obtained from a database and chart review. CT’s from fibrostenotic CD patients were sex and BMI matched to patients with only TI inflammatory behaviour. Patient demographics, medication, smoking, and surgical history were also obtained. Analyses were adjusted for age, sex, and BMI covariates. Unpaired t-tests and multi-variable logistic regression analyses were conducted.

Result(s)

Twenty-eight patients with stricturing CD had a significantly greater mean VAT:SAT volume ratio than 29 non-stricturing CD (41.5 cm³ vs 34.2 cm³, p=0.03). Thirty-six percent (10/28) of CD stricture patients had prior ileocolic resection with a mean disease duration of 13.5 years (range 0-48). The median ileal BWT (7.0 mm, range 4.0-13.0 mm) for the stricturing group was significantly greater than those with inflammatory behaviour (BWT 2.0 mm, p<0.0001). The median luminal diameter and PSD for the stricture group was 2.0 mm (range 0 - 14.0 mm), and 3.0 cm (range 1.0 - 7.3 cm), respectively.

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Conclusion(s)

Fibrostenotic TI CD patients have increased VAT:SAT ratios in comparison to those with only inflammatory behaviour. These pilot VAT:SAT results provide an initial foundation for further studies to assess its predictive role in responsiveness of medical or surgical therapies in stricturing CD.

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Disclosure of Interest

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A123 DEFINING CROHN’S DISEASE STRICTURES USING INTESTINAL ULTRASOUND COMPARED TO HISTOPATHOLOGY

Background

Fibrostenotic Crohn’s Disease (CD) is a challenging phenotype often leading to surgical resection. Diagnostic imaging is an invaluable tool to diagnose CD strictures. MRE (Magnetic Resonance Enterography) is the most widely used modality for evaluating strictures, but is limited by access and cost. The current definition of strictures is based only on MRE or CT (computed tomography). Strictures are defined as increased bowel wall thickness (BWT), narrowed luminal apposition, and pre-stenotic dilation &gt; 3cm according to CONSTRICT MR/CT expert consensus criteria. However, this definition has not been studied in intestinal US (IUS). IUS is a cost-effective, easily repeatable, and well-tolerated tool shown to have equal accuracy to MRE in diagnosing and monitoring CD.

Aims

The objective of this study was to assess the utility of identifying strictures with IUS using CONSTRICT definition.

Methods

In this retrospective pilot study, 30 of 80 CD patients who underwent small bowel resection (gold standard for stricture diagnosis) between 2015–2019 with IUS within 6 months prior to surgery were randomly identified for chart review. IUS was performed in a fasted state without oral contrast. Data extracted included confirmed stricture on resection specimens defined as having fibrosis and prestenotic dilation. Fistulizing disease was excluded. Student’s t-tests, sensitivities, specificities, positive (PNV) and negative predictive values (NPV) were calculated for IUS in detecting strictures.

Results

Of the 30 CD patients evaluated, 20 patients had fibrostenosis on pathology and IUS reports. Only 40% (8/20) met CONSTRICT criteria for stricture diagnosis on IUS, despite having a stricture on pathology. All patients had elevated BWT and luminal narrowing, but 60% (12/20) did not have prestenotic dilation &gt; 3cm. Mean dilation was 2.9 cm (SD 1.38) and was significantly different from the mean stricture diameter of 1.3cm (SD 0.59 cm, p=0.0001, 95% CI: 0.9–2.2). Mean BWT was 8.7 mm (SD: 2.5, range 5–15) where normal is &lt; 3mm, and mean luminal apposition was 2.3 mm (SD 1.2, range 0.2–5.8mm). IUS has a sensitivity of 95.2% (95% CI: 76.2 - 99.9%), specificity of 66.7% (95% CI: 29.9 - 92.5%), PPV of 87.0% (95% CI: 72.5–94.4), and NPV of 85.7% (95% CI 45.6–97.7%) in detecting strictures when compared to gold standard.

Conclusions

CONSTRICT criteria for diagnosing fibrostenotic CD on CT/MR may not be applicable to IUS. In this study, only 40% of patients met criteria despite having histologic confirmed strictures. Thus, perhaps additional criteria of stricture diameter &lt; 50% of prestenotic dilation size is most appropriate for IUS. This pilot study provides the initial data to delineate an IUS stricture definition for future validation and to inform both clinical practice and trial design.

Funding Agencies

None