Detection of Celiac Disease in Primary Care: A Multicenter Case-Finding Study in North America

Carlo Catassi, M.D., M.P.H.; Deborah Kryszak, B.S.; Otto Louis-Jacques, M.D.; Donald R. Duerksen, M.D.; Ivor Hill, M.D.; Sheila E. Crowe, M.D.; Andrew R. Brown, M.D.; Nicholas J. Procaccini, M.D.; Brigid A Wonderly, R.N.; Paul Hartley, M.D.; James Moreci, M.D.; Nathan Bennett, M.D.; Karoly Horvath, M.D., Ph.D.; Margaret Burk, R.N.; Alessio Fasano, M.D.

Disclosures

Am J Gastroenterol. 2007;102(7):1454-1460. 

In This Article

Abstract and Introduction

Abstract

Background: Celiac disease (CD) is one of the most common lifelong disorders in western countries. However, most cases remain currently undiagnosed in North America, mostly due to poor awareness of CD by primary care physicians.
Objectives: The aims of this study were (a) to determine whether an active case-finding strategy in primary care could increase the frequency of CD diagnosis and (b) to determine the most common clinical presentations of the condition.
Methods: This was a multicenter, prospective study involving adult subjects during the years 2002-2004, attending one of the participating practices. All individuals with symptoms or conditions known to be associated with CD were tested for immunoglobulin A anti-transglutaminase (tTG) antibodies, and those with elevated anti-tTG were subsequently tested for IgA antiendomysial antibodies (EMA). All subjects who were positive for EMA were advised to undergo an intestinal biopsy and HLA typing.
Results: The study group included 737 women and 239 men, with a median age of 54.3 yr. A positive anti-tTG test was found in 30 out of 976 investigated subjects (3.07%, 95% CI 1.98-4.16). CD was diagnosed in 22 patients (18 women, 4 men). The most frequent reasons for CD screening in these 22 cases were bloating (12/22), thyroid disease (11/22), irritable bowel syndrome (7/22), unexplained chronic diarrhea (6/22), chronic fatigue (5/22), and constipation (4/22). The prevalence of CD in the serologically screened sample was 2.25% (95% CI 1.32-3.18). The diagnostic rate was low at baseline (0.27 cases per thousand visits, 95% CI 0.13-0.41) and significantly increased to 11.6 per thousand visits (95% CI 6.8-16.4, P < 0.001) following active screening implementation.
Conclusions: This study demonstrates that an active case-finding strategy in the primary care setting is an effective means to improve the diagnostic rate of CD in North America.

Introduction

Celiac disease (CD) is an immune-mediated enteropathy caused by the ingestion of gluten-containing cereals (wheat, rye, and barley) in genetically predisposed individuals. In countries where most people are of European ancestry, CD is one of the most common lifelong disorders.[1] Recent epidemiological surveys in Europe and in the United States of America showed the prevalence of CD in the general population is between 0.5 and 1%.[2] Many cases remain undiagnosed, usually because they have atypical symptoms and because there is a lack of awareness of CD by doctors. In a large European survey, the ratio between diagnosed and undiagnosed cases (the latter found by mass serological screening) was as high as 1 to 7 (the so called "celiac iceberg").[3] In addition to having chronic symptoms that might otherwise respond to a gluten-free diet (GFD), undiagnosed patients are exposed to the risk of long-term complications of CD, such as anemia, infertility, osteoporosis, or cancer (especially intestinal lymphoma).

The diagnosis of CD is based on finding the characteristic histological features on small intestinal biopsy and a clinical response to the GFD. However, serological markers, e.g., the IgA class anti-tissue transglutaminase (tTG) antibodies, are useful screening tests. The sensitivity and the specificity of the IgA anti-tTG test are 94% and 97%, respectively.[4] Serological screening of the general population will identify most cases of previously unrecognized CD, but mass screening for CD is not currently recommended, as the potential cost/benefits of such a strategy have not been determined. An active case-finding strategy targeting both symptomatic and asymptomatic individuals who are at risk for CD is currently considered a more cost-effective approach to diagnosis.[5] The case-finding strategy has the following advantages compared with mass screening: (a) selective finding of subjects with health problems and poor quality of life, who can immediately benefit from treatment with a GFD, and (b) it is less expensive.[6]

The level of awareness of CD and its clinical polymorphism is low in the United States of America, although it has increased recently.[7] Serological testing for CD is currently not widely adopted by primary care physicians. In a recent nationwide study, a small bowel biopsy was not taken in the majority of patients (89%) undergoing gastroduodenoscopy because of possible symptoms of CD (anemia, iron deficiency, weight loss, or diarrhea).[8] Consequently, the majority of individuals with CD remain undiagnosed in the United States of America, with a calculated ratio of diagnosed to undiagnosed cases being as high as 1 to 50-100.[2]

A primary care practice provides the best opportunity to first identify individuals who are at risk for CD and need referral for definitive diagnosis. For this reason, we undertook a multicenter, prospective, case-finding study using serological testing of adults who were seeking medical attention from their primary care physician in the United States of America and Canada. The aims of this study were (a) to determine whether an active case-finding strategy could increase the frequency of CD diagnosis and (b) to determine the most common clinical presentations of the condition in this setting.

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