Diagnosing coeliac disease by rectal gluten challenge: a prospective study based on immunopathology, computerized image analysis and logistic regression analysis.

The purpose of this study was to evaluate the use of rectal gluten challenge in the diagnosis of coeliac disease. A total of 103 patients with features suggestive of this diagnosis were prospectively enrolled into the study; a diagnosis of coeliac disease was based on strictly defined criteria used in judging the proximal jejunal biopsy. On that basis, 45 out of the 103 patients were deemed to have coeliac disease. A slurry of gluten powder in physiological saline was introduced into the rectum, and biopsies taken before and at 2 h or 4 h after the challenge were examined immunohistochemically by computerized image analysis. Cell counts were analysed by logistic regression, and the best equations were obtained for each challenge group. The 2 h challenge yielded diagnostic sensitivity and specificity of 69.6% and 78.6% respectively. The 4 h challenge provided sensitivity and specificity of 100% and 100% respectively. These results were compared with other clinical diagnostic predictors,including anti-endomysial antibodies, which yielded diagnostic sensitivity and specificity of 70% and 98% respectively. It is concluded that a 4 h rectal challenge is a highly sensitive means of identifying gluten-sensitized individuals, and would be of particular value in cases showing negative antibody screening or equivocal biopsy appearances.