Gastroenterology

Gastroenterology

Volume 120, Issue 4, March 2001, Pages 827-833
Gastroenterology

Alimentary Tract
Comparative study of ASCA (Anti–Saccharomyces cerevisiae antibody) assays in inflammatory bowel disease,☆☆,

https://doi.org/10.1053/gast.2001.22546Get rights and content

Abstract

Background & Aims: Anti–Saccharomyces cerevisiae antibody (ASCA) is a serologic marker associated with Crohn's disease (CD). Although there is still discussion on its clinical value, several companies each promote their own ASCA assay to be used in the gastroenterologist's practice at considerable expense. The aim of this study was to determine whether different ASCA assays agree sufficiently well for the results to be used interchangeably. Methods: Blood obtained from a large cohort of IBD patients with inflammatory bowel disease (IBD; 100 with CD, 100 with ulcerative colitis [UC]) and 178 controls (100 healthy blood donors and 78 patients with non-IBD diarrheal illnesses) was studied with 4 different ASCA assays. Sensitivity, specificity, and positive predictive value were compared. Agreement between assays was evaluated. Results: Sensitivity of ASCA for CD ranged between 41% and 76%. Sensitivity was inversely related to specificity and positive predictive value. Results correlated well overall (range = 0.54–0.90) and the different ROC curves showed good agreement. When recalculated cutoff points were used, interchangeability increased. However, large differences were seen when absolute values were compared. Conclusions: A large range in sensitivities and specificities of ASCA for CD is seen with different ASCA assays, mainly as a consequence of the cutoff value chosen for each individual assay. Although agreement between and within assays is good, caution is important when absolute values are used. Standardization of ASCA measurements is greatly needed.

GASTROENTEROLOGY 2001;120:827-833

Section snippets

Study population

Analyses were performed in a cohort of 200 unselected patients with IBD and 178 controls, using the different ASCA assays. The IBD patients included 100 patients with CD (57 female, 43 male; mean age, 38.5 years; age range, 15–78 years) and 100 with ulcerative colitis (UC; 46 female, 54 male; mean age, 40.6 years; age range, 18–73 years). The diagnosis was made according to the Lennard-Jones criteria,9 and all patients were carefully classified. Clinical characteristics are summarized in Table

Results

The range of ASCA titers and mean ASCA in CD varied substantially between the different assays. For the Prometheus Laboratories assay, mean ASCA IgA was 51.80 (±38.9; range, <12.5–121.3) and mean ASCA IgG was 80.6 (±70.0; range, <12.5–323.2). Using the Medipan assay, mean ASCA IgA was 1.51 (±2.0; range, 0.12–8.44) and ASCA IgG was 0.81 (±0.85; range, 0.08–3.3). The ASCA results from Lille ranged from 0.26 to 76.29, with a mean titer of 7.23 (±11.5). Inova mean ASCA IgA was 42.34 (±41.35; range,

Discussion

Antibodies against the yeast S. cerevisiae, a yeast commonly used in the food industry, are found in CD with a prevalence varying from 55% to 65%. The specificity for CD is higher, with reported figures of 80%–95%. However, data are still scarce and come from different research groups mostly using different assays. Nevertheless, several commercial companies recently developed an ASCA assay and promote its use in IBD clinical practice. The use of these tests involves an important financial

Acknowledgements

The authors thank the laboratories and companies that collaborated in this study by providing the ASCA kits: Dr. D. Poulain and Dr. B. Sendid (Laboratoire de Parasitologie-Mycologie, CHRU Lille, France), Prometheus Laboratories Inc. (San Diego, California), Medipan Diagnostica (Selchow, Germany) distributed by Euribel S.A./N.V. (Brussels, Belgium), and Inova Diagnostics (San Diego, California) distributed by Medigal S.A. (Villers-Poterie, Belgium).

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Supported by a grant of the Funds for Scientific Reasearch (FWO), Brussels, Belgium, and a grant by A. Lazzari. S Vermeire is an aspirant of the FWO Belgium.

☆☆

Address requests for reprints to: Paul Rutgeerts, M.D., Department of Gastroenterology, UZ Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium. e-mail: [email protected]; fax: (32) 16-34-43-99.

Drs. Vermeire and Joossens contributed equally to this work.

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