QJM Advance Access originally published online on June 14, 2006
QJM 2006 99(7):453-460; doi:10.1093/qjmed/hcl061
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The epidemiology of coeliac disease in East Dorset 1993–2002: An assessment of the ‘coeliac iceberg’, and preliminary evidence of case clustering
From the 1Division of Infection, Inflammation and Repair, University of Southampton, Southampton General Hospital, Southampton, and 2Dorset Research and Development Support Unit and 3Department of Gastroenterology, Poole Hospital, Poole, UK
Address correspondence to Dr A.J. Fowell, Division of Infection, Inflammation and Repair, University of Southampton, Mailpoint 811, Southampton General Hospital, Tremona Road, Southampton SO16 6YD. email: afowell{at}hotmail.com
Received 19 December 2005 and in revised form 24 March 2006
Background: Coeliac disease (CD) results from mucosal exposure to dietary gluten in genetically predisposed individuals, although other environmental factors may be involved. The seroprevalence of CD is approximately 1%, with a high ratio of undiagnosed to diagnosed cases, leading to the concept of a ‘coeliac iceberg’.
Aim: To provide contemporary estimates of the incidence of diagnosed CD and the size of the submerged ‘coeliac iceberg’, and to seek evidence of disease clustering.
Design: Prospective observational study in a defined local population.
Methods: Data were collected prospectively for all biopsy-proven cases diagnosed at Poole Hospital, 1993–2002. Age-specific incidence was calculated and point prevalence estimated for cases within the defined study zone. Evidence of disease clustering was sought using a space-time scan statistic based on a Poisson model.
Results: The overall incidence of CD was 8.7 cases/100 000/year (95%CI 7.4–10.1), with a median age at diagnosis of 53 years. Incidence increased progressively during the study period, and the estimated point prevalence of biopsy-proven CD rose from 0.18% to 0.4%. An area of significant space-time clustering was identified, with an incidence of 22.9 cases/100 000/year (95%CI 16.1–31.6), but there was no evidence of seasonality.
Discussion: The submerged component of the ‘coeliac iceberg’ may be diminishing due to increasing case ascertainment, with a projected ratio of undiagnosed to diagnosed cases as low as 1.5:1. Our identification of clustering must be interpreted with caution, but suggests that an additional environmental factor may influence the pathogenesis of CD.