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Screening for celiac disease: the continuous dilemma
- Silvia Salvatore, Chiara Citro, Serena Arrigo, Chiara Luini, Patrizia Marino, Mara Salmaso, Luigi Nespoli (13 December 2007)
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Screening for coeliac disease – feasible and accurate but where does this novel technology take us?
- David S Sanders, Andrew D Hopper, John S Leeds, Marios Hadjivassiliou (17 December 2007)
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Caution required in promotion of OTC self-testing for Coeliac Disease
- PETER M GILLETT (30 December 2007)
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Silvia Salvatore, Lecturer in Pediatrics Dpt of Pediatrics, Università dell'Insubria, Osp., Chiara Citro, Serena Arrigo, Chiara Luini, Patrizia Marino, Mara Salmaso, Luigi Nespoli
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The paper of Korponay-Szabó et al. (1) highlights once more (2) (3) the importance of a population screening program to early detect celiac patients. Although celiac disease (CD) satisfies 5 out of 5 major WHO criteria for mass screening, only a case finding approach for symptoms and/or conditions known to be associated with CD is the currently "best buy" recommendation mainly because of economical and ethical reasons. However, under diagnosis of CD disease is still common because of low awareness of CD in general practice and often results in protracted and unnecessary morbidity. At least one clinical sign of CD was present in 23 out of 28 children diagnosed with CD at screening (1) but investigation for CD had not been previously performed in these subjects. In the last years the tissue transglutaminase antibodies showed both sensitivity and specificity of more than 93% and have been recently considered as the optimal test for screening CD (4). Nowadays the finger prick blood test offers a simple, fast, cheap and accurate serological test for CD (1) and, hopefully, would permit an easier screening for CD in pediatric ages. In Italy, fast tests for urine, Streptococcus and Rotavirus infection and serum glucose and CRP are already available in the office of family paediatricians speeding up the diagnostic and therapeutic process. It is auspicious that this fast test for CD could both improve their consciousness about CD and be also part of their diagnostic armamentarium in the next future. 1. Korponay-Szabó IR, Szabados K, Pusztai J, Uhrin K, et al. Population screening for coeliac disease in primary care by district nurses using a rapid antibody test: diagnostic accuracy and feasibility study. BMJ published online 6 Dec 2007; doi:10.1136/bmj.39405.472975.80 2. Bingley PJ, Williams AJK, Norcross AJ, Unsworth DJ, et al. Undiagnosed coeliac disease at age seven: population based prospective birth cohort study. BMJ 2004;328;322-323 3. Hin H, Bird G, Fisher P, Mahy N, Jewell D. Coeliac disease in primary care: case finding study. BMJ 1999;318;164-167 4. Gomez JC, Selvaggio G, Pizarro B, et al. Value of a screening algorithm for celiac disease using tissue transglutaminase antibodies as first level in a population-based study. Am J Gastroenterol 2002;97:2785–90. Competing interests: None declared |
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David S Sanders, Consultant Gastroenterologist Royal Hallamshire Hospital, Sheffield, Glossop Road, S10 2JF, Andrew D Hopper, John S Leeds, Marios Hadjivassiliou
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We read with interest this excellent paper pertaining to screening children using point of care testing for coeliac disease.1 Although the authors suggest that these children had clinical problems found in untreated coeliac disease and benefited from the diagnosis (after 6 months on a GFD) – despite this we would still advocate caution. It is fair to say that coeliac disease fulfils the tenets of any screening programme, however, we do not know the natural history of screen-detected patients with coeliac disease. It may be that the individuals recognised through screening have a more indolent clinical manifestation of the disease and that untreated coeliac disease may even confer a biological advantage in adulthood (lower cholesterol or blood pressure).2 Although the investigational process for population screening and case- finding maybe the same, there is an important ethical difference between them. If a patient seeks medical help then the physician is attempting to diagnose the underlying condition (for example: patients with coeliac disease who present with symptoms of irritable bowel syndrome). This would be classified as case-finding and clearly it is the patient who has initiated the consultation and in some sense is consenting for investigation. Conversely, individuals (who are not patients) found to have coeliac disease through screening programmes, may have considered themselves as ‘well’ and it is the physician or healthcare system that is identifying them as potentially ill. We recently performed a primary care based cross-sectional study using serological markers (endomysial and gliadin antibodies) to initially recognise coeliac disease.3 1200 adult volunteers were recruited from January 1999 to June 2001 from 5 General Practices in South Yorkshire, United Kingdom. Any participant with a positive serological result was offered a small bowel biopsy to confirm the diagnosis of coeliac disease. Twelve new cases of coeliac disease were diagnosed from 1200 samples. The prevalence of coeliac disease in this primary care population sample is 1% (95% CI 0.4-1.3%).1 In this screening study, 9/12 diagnosed cases of coeliac disease ultimately had subtle symptoms which could be attributed to coeliac disease (for example, anaemia or subtle gastrointestinal symptoms). Five years later 5/12 screen detected patients are no longer complying with the gluten-free diet. We, and others have demonstrated a delay in the diagnosis of coeliac disease – surely the important change in our clinical practice (both in primary and secondary care) is to have a low threshold for case-finding. Now that point of care testing is here we must be cautious about how we advocate its use – if this test is available over the counter there is a risk that individuals will test and treat themselves without ever seeking healthcare professionals’ advice or even a duodenal biopsy. With excellent technology comes the burden of increased responsibility. References 1. Korponay-Szabó IR, Szabados K, Pusztai J, Uhrin K, Ludmány E, Nemes E et al. Population screening for coeliac disease in primary care by district nurses using a rapid antibody test: diagnostic accuracy and feasibility study. BMJ 2007;335:1244-1247. 2. West J, Logan RF, Card TR, Smith C, Hubbard R. Risk of vascular disease in adults with diagnosed coeliac disease: a population-based study. Aliment Pharmacol Ther 2004;20:73-9. 3. Sanders DS, Patel D, Stephenson TJ, Milford-Ward A, McCloskey EV, Hadjivassiliou M, Lobo AJ. A primary care cross-sectional study of undiagnosed adult coeliac disease. Eur J Gastroenterol Hepatol 2003 Apr;15(4):407-13. Competing interests: None declared |
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PETER M GILLETT, Consultant Paediatric Gastroenterologist RHSC Edinburgh, Sciennes Road, Edinburgh EH9 1LF
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This recent paper represents a follow-up after the initial paper by Maki et al in 2006 (Aliment Pharmacol Ther 24, 147-154), where they demonstrated 96.7% sensitivity and 93.5% specificity in a wide age range (1.6 to 68 yrs) and suggested that it may be useful in monitoring dietary lapses in follow-up in addition to its comparable utility for intial diagnosis. That initial study also suggested that the test was good for a sub-group of patients with subsequently very subtle biopsy findings. In this study, District nurses did the testing, (apparently untrained but in any case should have got better as they used it) and reveals a disappointing 78.1% sensitivity but excellent specificity of 100% in a 6 year old population (not recommended under this age, despite it being used in under 6 year olds in the initial study). Like Endomysial testing, the result is truly in the eye of the beholder! A screening test like this needs to be Sensitive , that is, to pick up cases and ideally not miss any - this study does not reassure me that in over the counter practice(that is the general public, self-testing) this is as valuable as previously reported and enthusiasm for its general population use needs to be tempered. I am also sure that some patients would not then seek further advice despite this being given by the companies selling it. It may well lead to false reassurance, even in the face of symptoms. In addition, the majority of my new cases per year are below age 6 so for childhood use it's not helpful (i have many children sent for advice and testing when a parent is Coeliac). We used some of the Biocard kits in an informal study: in a girl age 6, undergoing a gluten challenge (and symptomatic), this kit was negative, when our laboratory test (same sample) was positive, AutoDELFIA IgA tTG 33.2 AU (normal <7.9), the biopsy confirming partial villous atrophy. The marketing of this test is very reasonable and on one site has a rider that it isn't recommended under 5 years of age. It is easy enough to use, but certainly isnt cheap in the UK (at £19.99) and this recent study does not make me want to recommend it to anyone (child or parent)for self- diagnosis when rapid access to blood testing in a validated lab is part of the UK system. I agree completely with Sanders et al that our aim should be far better case finding in conjunction with patient (and Healthcare provider) education through interested individuals, Coeliac UK (and Government)and easy access to NHS lab testing that has better sensitivity than this test appears to have in practice. I am also sceptical about population screening, even though Coeliac disease does push that button. I agree that in a large number of screening diagnosed cases (Type I diabetic children are a prime example) adherence to diet is not great and many would not thank you for the second diagnosis, however well intentioned that may have been! Counselling of concerned patients, families,quantifying risk and offering formal NHS testing for those who remain worried should be our goal in the UK. Competing interests: None declared |
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