Does dietary advice based on food allergy tests improve disease control in children with eczema? Trial of food allergy IgE tests for Eczema Relief (TIGER) study protocol

Conference:

SAPC ASM 2023 - Brighton

Talk Code:

6B.1

Presenter:

Catherine Woods

Co-authors:

Matthew Ridd, Stephanie MacNeill, Yumeng Liu, Miriam Santer, Tom Blakeman, Hannah Wardman, Ingrid Muller, Joanna Coast, Kirsty Garfield, Robert Boyle, Rosan Meyer, Isabel Skypala, Shoba Dawson, Hannah Morgans, Julie Clayton, Sara Brown, Hywel Williams

Author institutions:

University of Bristol, University of Southampton, University of Manchester, Imperial College London, University of Nottingham, University of Edinburgh, Royal Brompton & Harefield Hospitals

Problem

Many parents worry that a food allergy is the underlying cause for their child’s eczema and ask doctors about allergy tests. Most GPs refer to a specialist for these but wait times are long and use of allergy tests varies. A previous trial suggested that infants with eczema who have a positive allergy test for egg may benefit from an egg-free diet, but a larger, better-designed study is needed. The aim of this study is to determine the clinical and cost effectiveness of test-guided dietary advice versus standard care, for eczema management.

Approach

Pragmatic, multi-centre, parallel group, individually randomised controlled trial (ISRCTN52892540), with internal pilot and nested economic and process evaluations. Children (<2 years) with mild or worse eczema will be recruited from ~84 GP surgeries and randomised 1:1 to comparator or intervention groups. All participants will receive our “Good eczema care” leaflet. Those in the intervention group will also undergo skin prick tests to milk, wheat, egg and soy, and advised to eliminate any foods to which they are sensitised for 4 weeks.

The primary perspective of a health economic analysis will be NHS. A cost-utility analysis will compare quality-adjusted life years (QALYs) gained for the child and main carer to costs incurred by the NHS. Additionally, costs from NHS and non-NHS perspectives will be related to a range of outcomes in a cost-consequences approach.

A nested process evaluation will employ qualitative and quantitative methods to assess intervention fidelity, clarify causal mechanisms, and identify contextual factors associated with variation in outcomes. We will conduct in-depth interviews with ~15 GPs, ~15 Research and Practice Nurses, and ~30 parents. Nurse training sessions will be observed and recruitment visits audio-recorded. We will explore quantitatively potential mediators of adherence and intervention outcomes.

Findings

493 participants will be followed up over 36 weeks. The primary outcome is eczema control, measured by the parent completed RECAP, collected four-weekly over 24 weeks. Secondary outcomes include: eczema symptoms; quality of life; adverse events; breastfeeding status and diet; growth; parental anxiety.

The primary analysis will be a multilevel mixed model framework with observations over time nested within participants.

Consequences

This study will fill an evidence gap of importance to patients and carers, and reduce variation in practice and associated harms.

Submitted by:

Matthew Ridd

Funding acknowledgement:

Funded by the NIHR HTA (NIHR133464). The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.