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Changes in Testing for and Incidence of Celiac Disease in the United Kingdom

A Population-based Cohort Study

West, Joe; Otete, Harmony; Sultan, Alyshah A.; Crooks, Colin J.

doi: 10.1097/EDE.0000000000001006
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Division of Epidemiology and Public Health, University of Nottingham, Nottingham, United Kingdom, joe.west@nottingham.ac.uk, NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust, University of Nottingham, Nottingham, United Kingdom

School of Pharmacy, University of Nottingham, Nottingham, United Kingdom, School of Medicine and Dentistry, University of Central Lancashire, Preston, United Kingdom

Research Institute for Primary Care & Health Sciences, Primary Care Sciences, Keele University, Staffordshire, United Kingdom

NIHR Nottingham Biomedical Research Centre, Nottingham University Hospitals NHS Trust, University of Nottingham, Nottingham, United Kingdom, Nottingham Digestive Diseases Centre, School of Medicine, University of Nottingham

Funded by Coeliac UK.

The authors report no conflicts of interest.

All authors meet the following criteria in that they carried out substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; and drafting the work or revising it critically for important intellectual content; and final approval of the version to be published; and agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Data and code: The data used in the article were acquired from the Clinical Practice Research Datalink under a license to the University of Nottingham. These data are not permitted to be distributed to third parties, but are available from CPRD following acquisition of the appropriate approvals and payment.

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To the Editor:

The diagnosis rates of celiac disease differ substantially between countries.1 Intriguingly, there has been recent evidence from Olmstead County, United States, and Finland that in the last 5–10 years incidence has leveled off or even declined.2,3 In most populations, the prevalence also varies widely with serologic prevalence from 0% to 1.87% and clinical prevalence from 0.9 to 12.9 per 100,000.1 Understanding of why this variation exists is minimal, yet one of the key aspects governing incidence rates of any disease are factors related to the health system, such as the availability and use of diagnostic tests. We previously reported rising incidence rates of celiac disease4 from 1990 to 2011 with differences related to socioeconomic deprivation in the United Kingdom. Although national guidance on recognition and diagnosis of celiac disease published in 20095 suggested widening the patient groups that should be tested for celiac disease, National Health System (NHS) financial constraints could have hindered implementation of these guidelines. Indeed, in the United States researchers have observed that over the period 2000–2010 there was a marked decrease in the treated prevalence of many diseases alongside a sustained period of reduced spending on health care.6

We used the UK Clinical Practice Research Datalink GOLD (Independent Scientific Advisory Committee approval 16_130) to estimate the European (EUROSTAT EU-27 plus EFTA 2013 population7) age-standardized incidence rates of celiac disease8 2005–2015 and the corresponding rates of serologic testing (anti-tissue transglutaminase antibody and anti-endomysial antibody) for the disease. We used Joinpoint analysis9 to examine statistical evidence of changes in the rates of diagnosis and testing during this period. We estimated celiac disease point prevalence based on all contributing patients at 30 June 2015 and estimated incidence rate ratios using Poisson regression for testing and incidence rates.

There were 8177 incident cases of celiac diseases diagnosed among 45,539,211 million person-years. The overall incidence rate between 2005 and 2015 was 18 per 100,000 person-years, serological testing rate was 118 per 100,000 person-years, and point prevalence on the 30 June 2015 was 0.30% (95% confidence interval [CI] = 0.30, 0.31). Incidence rates of celiac disease were highest in people aged between 60 and 69 years (23 per 100,000 person-years), whereas the rate of serologic testing was highest in those aged 20–29 years (233 per 100,000 person-years). For the calendar period 2005–2015 there was an increase in European age-standardized incidence rates from 2005 to 2012 and then a plateau effect (Figure 1). Serologic testing increased and then decreased during the same period (Figure 2). Joinpoint analysis identified that there were changes in the rates of both diagnosis and testing at 2012 (95% CI = 2007, 2013) and 2011 (95% CI = 2010, 2013), respectively. The Joinpoint analysis is presented in the Table.

TABLE

TABLE

FIGURE 1

FIGURE 1

FIGURE 2

FIGURE 2

In this study, we found that European age-standardized rates of diagnosis of celiac disease and serological testing have, since 2011, respectively leveled off and declined, while prevalence increased from 0.24%4 to 0.3%.

This could be because, since 2010, the UK NHS has been operating under a period of financial austerity. While health funding has been forecast to grow 1.2% in real terms between 2009/10 and 2020/21, this is below the long-term average increase in health spending of approximately 4% a year since the NHS was established in 1948.10 Alternatively, clinicians based in primary care could be carrying out more targeted use of testing in certain age or at-risk groups, leading to an overall reduction in testing. We may have missed some tests carried out in secondary care as we did not have access to these. We found some evidence that testing did vary by age, disproportionately to disease incidence, in that the highest testing rate was in those aged 20–29 years yet the highest incidence rate was in the 60–69-year-old group. Finally, it is possible that following several years of increasing diagnosis rates before 20114 that the threshold of clinically identifiable celiac disease in the United Kingdom has been reached and a steady-state incidence rate obtained.

Joe West

Division of Epidemiology and Public Health

University of Nottingham

Nottingham, United Kingdom

joe.west@nottingham.ac.uk

NIHR Nottingham Biomedical Research Centre

Nottingham University Hospitals NHS Trust

University of Nottingham

Nottingham, United Kingdom

Harmony Otete

School of Pharmacy

University of Nottingham

Nottingham, United Kingdom

School of Medicine and Dentistry

University of Central Lancashire

Preston, United Kingdom

Alyshah A. Sultan

Research Institute for Primary Care & Health Sciences, Primary Care Sciences

Keele University

Staffordshire, United Kingdom

Colin J. Crooks

NIHR Nottingham Biomedical Research Centre

Nottingham University Hospitals NHS Trust

University of Nottingham

Nottingham, United Kingdom

Nottingham Digestive Diseases Centre

School of Medicine

University of Nottingham

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