Expanding the eligibility criteria for a no-biopsy diagnosis for coeliac disease in adults and children: Individual participant data review and cost-effectiveness analysis.

Research question How can we expand the no-biopsy criteria for diagnosing coeliac disease (CD) in adults and children? Background

CD is a common autoimmune disorder triggered by ingesting gluten in susceptible individuals. CD is diagnosed with a blood test followed by a biopsy, which is invasive, not tolerated well by patients, and there are long waiting times for appointments.

No-biopsy pathways have been developed for children and similar pathways were adopted for adults during the pandemic. These pathways are believed to be safe, lead to quicker diagnoses, and earlier start of treatment.

There is scope for expanding the eligibility criteria for no-biopsy pathways, so that more patients can benefit from them and NHS resources can be used more effectively. However, this needs to be balanced against the risk of false positives to avoid people following a gluten free diet unnecessarily.

Aims and Objectives

To determine the accuracy and cost-effectiveness of serological tests at different thresholds, singly and in combination, to optimise no-biopsy pathways for CD diagnosis in children and adults. Methods We propose an evidence synthesis consisting of four integrated work packages (WP):

1 Individual participant data (IPD) review and meta-analysis to estimate the accuracy of serological tests for CD at different thresholds and in different combinations (WP1). We will request serological test data and biopsy results from cohort studies.

2 We will develop no-biopsy pathways with clinicians and patients (WP2). The pathways will be informed by a discrete choice experiment and a Delphi panel of stakeholders, including clinicians and patients.

3 A laboratory survey to estimate the range of costs and availability of serological tests for CD amongst UK labs (WP3). We will collect information on the availability and cost of tests, result turn-around times, testing kits, and how results are reported (qualitative or quantitative).

4 Health economic modelling to estimate the cost-effectiveness of selected diagnostic strategies including different sets of eligibility criteria for no-biopsy pathways (WP4). We will build on our existing economic model, with the diagnostic test accuracy estimates from WP1 and the costs of the serological tests from WP3. We will estimate the cost-effectiveness of each pathway developed in WP2, as well as how many biopsies can be avoided, how many CD patients may be missed or put on a gluten free diet unnecessarily, and what the time will be between CD suspicion and diagnosis.

Timelines for delivery

Study duration will be 24 months from 1 June 2024. Key milestones: ethical approval WP1 (Month 4); refined clinical pathways WP2 (Month 10); data sharing agreements WP1 (Month 12); IPD analysis WP1 (Month 18); ethical approval lab survey WP3 (Month 18); health economic modelling (Month 16); report submission (Month 24).

Anticipated impact and dissemination

We anticipate a minimum of four peer reviewed articles; one for each WP. We will work with our PPI team and comms officer to produce a plain language summary and visual infographics. Coeliac UK will help us to disseminate these to patients. Team members who sit on NICE, ESPGHAN, BSG, and ESsCD guideline committees will help communicate our findings to the relevant guidelines.

The anticipated impacts are to change guidelines and practice, which could mean shorter waiting times for biopsies, quicker diagnosis and earlier treatment for CD patients, and cost savings for NHS.