Some decades ago, celiac disease (CD) was seen as a rare childhood disease and new cases were only found with the presentation of typical symptoms (1). Sensitive serological tests now make it possible to diagnose cases that previously would have gone undetected, and, subsequently, CD has emerged as a global public health problem. The clinical symptoms vary greatly, both between individuals and within the same individual over time, and are most obvious in infancy. Many cases are diagnosed in adulthood and may have gone undetected for a long time, with the person having become accustomed to a state of vague ill health. These undetected cases are sometimes inappropriately called “silent.”
The prescribed treatment of CD is a lifelong gluten-free diet (GFD); in other words, all foods containing wheat, rye, and barley must be removed from the diet (1). There is ongoing debate about how stringent the gluten restriction needs to be. For instance, in many European countries, foods labeled gluten free can include wheat starch. This ingredient has been rendered gluten free but still contains small amounts of prolamins, the toxic agent in CD. The amounts of prolamins allowed is regulated in the Codex Alimentarius, a revision of which was established this past summer. By contrast, only naturally gluten-free foods can be labeled gluten free in the United States and Canada; products containing wheat starch would be labeled “low gluten.”
Whether the GFD is naturally gluten free or also includes low gluten products, complying with the diet entails major changes in what most patients eat. How difficult patients perceive this to be depends on many factors: the composition of their original diet; the availability and palatability of gluten-free alternatives; the number and severity of symptoms after transgressions; age at diagnosis; present age; patients' and others' knowledge about CD; support from relatives, friends, and health care staff; and economic factors. In a recent study, Olsson et al (2) found that eating at home was rarely regarded as a problem by Swedish adolescents with CD, whereas eating out was more difficult. One of the reasons for problems outside the home was lack of knowledge about the disease among staff in canteens and restaurants. Karajeh et al (3) reported a similar problem among chefs in the United Kingdom.
Evaluation of patient quality of life (QoL) has become more important in health care practice and research in the last 50 to 60 years (4). Health-related quality of life (HRQoL) measures the patient's own perception of his or her QoL in several domains affected by health status: social and physical functioning, somatic sensations, and social interactions (5). There are several different instruments to measure HRQoL generally (6). Generic instruments such as the Short Form Health Survey (SF-36), are used for comparisons between different diseases or with healthy controls. Disease-specific instruments are more sensitive to changes in the patient's health and different factors relevant to the specific disease. Recently, Häuser et al (7) developed the first validated disease-specific instrument for measuring HRQoL in adult patients with CD, and Van Doorn et al (8) developed one for children. To enable comparisons between groups it is important to use both generic and disease-specific questionnaires.
Whether HRQoL is influenced by how well the patient complies with the diet is debated. In a German study, Häuser et al (9) found that reduced HRQoL was associated with noncompliance in adults. By contrast, no such associations were found neither in Swedish patients (10) nor Italians (11). In this issue of the Journal, Wagner et al (12) reports on decreasing general QoL with decreasing compliance in adolescents, as well as equal QoL in compliant patients and healthy controls. In addition, some studies have found differences between men and women (10), whereas others have not (11).
There are problems in the comparisons of HRQoL between different studies, mainly because different instruments have been used. In addition, compliance with the GFD is probably affected by differences in food habits between countries as well as differences in the definition of gluten free (ie, whether only naturally gluten-free products are allowed in the diet or if products rendered gluten free can also be included, thus providing a larger choice of products). Whether oats are included in the diet also affects the diversity of choice (13). The levels of gluten restriction in the GFD could affect HRQoL in 2 opposed ways. A more stringent definition can be positive in terms of decreasing the risk for damaging intestinal mucosa but negative in terms of decreasing the variety of available foods and thereby making social life more restricted. In addition, gluten-free foods are often less palatable than comparable products in the normal diet because gluten is a crucial structure-forming component in baked products, and is also important for the taste and texture of other products containing flour (14).
Another concern is that when compliance is good, nutrient intake is often not satisfactory because the patient eats more fat (especially saturated) and sugar than is desirable (15–18). In the long run, this could increase the risk for other diet-related diseases. Thompson et al (19) point out that it is important for dietitians to avoid focusing too much on foods that are allowed or are not allowed. They should also emphasize the nutritional content of the whole diet. It is also of concern that the vitamin and mineral content of foods is often lower in gluten-free varieties than in their gluten-containing counterparts (20,21). However, the rising demand for these products with the increasing numbers of patients with CD has brought about advances in the formulation of gluten-free cereal-based products, which probably will affect both the nutritional content of these products and compliance with the GFD (14).
The possibility of diagnosing CD in people without overt symptoms makes the matter of QoL a more crucial question. Certainly, when “silent” cases are diagnosed, it has been shown that patients often perceive an improved health status after starting a GFD (22), although this may change with time (10). Screening studies show that there may be 3 to 7 undiagnosed cases for each diagnosed case, giving a prevalence of 0.7%–2.0% in most populations (23), and CD meets most of the requirements stated for mass screening (24,25). However, the benefits of mass screening have been questioned (26,27), and active case finding suggested as a viable option (28,29). An ongoing Swedish multicenter study (ETICS, Exploring The Iceberg of Celiac Disease in Sweden) has found a much larger prevalence of CD than expected among children born in 1993 (30). As many as 3% of the screened children had CD, with 2 of 3 previously undiagnosed. It is hoped that the study will shed light on whether mass screening would be beneficial in terms of health economics. Clearly, the QoL issues raised by Wagner (12) will remain high on the agenda for effective CD management practices for some time to come.
The author thanks Prof Phil Lyon for kindly checking the language of an earlier draft of the manuscript.
1. Fasano A, Catassi C. Current approaches to diagnosis and treatment of celiac disease: an evolving spectrum. Gastroenterology 2001; 120:636–651.
2. Olsson M, Hörnell A, Ivarsson A, et al
. The everyday life of adolescent celiacs—issues of importance for compliance with the gluten-free diet. J Hum Nutr Diet 2008; 21:359–367.
3. Karajeh MA, Hurlstone DP, Patel TM, et al
. Chefs' knowledge of coeliac disease (compared to the public): a questionnaire survey from the United Kingdom. Clin Nutr 2005; 24:206–210.
4. Testa MA, Simonson DC. Assesment of quality-of-life outcomes. N Engl J Med 1996; 334:835–840.
5. Eisen GM, Locke GR 3rd, Provenzale D. Health-related quality of life: a primer for gastroenterologists. Am J Gastroenterol 1999; 94:2017–2021.
6. Borgaonkar MR, Irvine EJ. Quality of life measurement in gastrointestinal and liver disorders. Gut 2000; 47:444–454.
7. Häuser W, Gold J, Stallmach A, et al
. Development and validation of the Celiac Disease Questionnaire (CDQ), a disease-specific health-related quality of life measure for adult patients with celiac disease. J Clin Gastroenterol 2007; 41:157–166.
8. Van Doorn R, Winkler L, Zwinderman K, et al
. The CDDUX: a disease-specific health-related quality-of-life questionnaire for children with celiac disease. J Pediatr Gastroenterol Nutr 2008; 47:147–152.
9. Häuser W, Stallmach A, Caspary WF, et al
. Predictors of reduced health-related quality of life in adults with coeliac disease. Aliment Pharmacol Ther 2007; 25:569–578.
10. Hallert C, Granno C, Grant C, et al
. Quality of life of adult coeliac patients treated for 10 years. Scand J Gastroenterol 1998; 33:933–938.
11. Fera T, Cascio B, Angelini G, et al
. Affective disorders and quality of life in adult coeliac disease patients on a gluten-free diet. Eur J Gastroenterol Hepatol 2003; 15:1287–1292.
12. Wagner G, Berger G, Sinnreich U, et al
. Quality of life in adolescents with treated celiac disease: the influence of compliance and age at diagnosis. J Pediatr Gastroenterol Nutr 2008; 47:555–561.
13. Troncone R, Auricchio R, Granata V. Issues related to gluten-free diet in coeliac disease. Curr Opin Clin Nutr Metab Care 2008; 11:329–333.
14. Gallagher E, Gormley T, Arendt E. Recent advances in the formulation of gluten-free cereal-based products. Trends Food Sci Technol 2004; 15:143–152.
15. Bardella MT, Fredella C, Prampolini L, et al
. Body composition and dietary intakes in adult celiac disease patients consuming a strict gluten-free diet. Am J Clin Nutr 2000; 72:937–939.
16. Hallert C, Grant C, Grehn S, et al
. Evidence of poor vitamin status in coeliac patients on a gluten-free diet for 10 years. Aliment Pharmacol Ther 2002; 16:1333–1339.
17. Mariani P, Viti MG, Montuori M, et al
. The gluten-free diet: a nutritional risk factor for adolescents with coeliac disease? J Pediat Gastroenterol Nutr 1998; 27:519–523.
18. Hopman EG, le Cessie S, von Blomberg BM, et al
. Nutritional management of the gluten-free diet in young people with celiac disease in the Netherlands. J Pediatr Gastroenterol Nutr 2006; 43:102–108.
19. Thompson T, Dennis M, Higgins LA, et al
. Gluten-free diet survey: are Americans with coeliac disease consuming recommended amounts of fibre, iron, calcium and grain foods? J Hum Nutr Diet 2005; 18:163–169.
20. Thompson T. Thiamin, riboflavin, and niacin contents of the gluten-free diet: is there cause for concern? J Am Diet Assoc 1999; 99:858–862.
21. Thompson T. Folate, iron, and dietary fiber contents of the gluten-free diet. J Am Diet Assoc 2000; 100:1389–1396.
22. Fabiani E, Catassi C, Villari A, et al
. Dietary compliance in screening-detected coeliac disease adolescents. Acta Paediatr Suppl 1996; 412:65–67.
23. Rewers M. Epidemiology of celiac disease: what are the prevalence, incidence, and progression of celiac disease? Gastroenterol 2005; 128(Suppl 1):S47–S51.
24. Bonita R, Beaglehole R, Kjellström T. Basic Epidemiology. 2nd ed. Geneva: World Health Organization; 2006.
25. Mearin ML, Ivarsson A, Dickey W. Coeliac disease: is it time for mass screening? Best Pract Res Clin Gastroenterol 2005; 19:441–452.
26. Collin P. Should adults be screened for celiac disease? What are the benefits and harms of screening? Gastroenterology 2005; 128(Suppl 1):S104–S108.
27. Hoffenberg EJ. Should all children be screened for celiac disease? Gastroenterology 2005; 128(Suppl 1):S98–S103.
28. Mulder CJ, Bartelsman JF. Case-finding in coeliac disease should be intensified. Best Pract Res Clin Gastroenterol 2005; 19:479–486.
29. Collin P, Huhtala H, Virta L, et al
. Diagnosis of celiac disease in clinical practice: physician's alertness to the condition essential. J Clin Gastroenterol 2007; 41:152–156.
30. Ivarsson A, Myléus A, Wall S. Towards preventing celiac disease—an epidemiological approach. In: Fasano A, Branski D, editors. Frontiers in Celiac Disease. Basel: Karger; 2008.