Trial of IGe tests for Eczema Relief (TIGER): randomised controlled trial of test-guided dietary advice for children with eczema, with internal pilot and nested economic and process evaluations

BACKGROUND: Parents commonly seek food allergy tests or restrict diets, to find a cause for their child’s eczema, yet the value of test-guided dietary advice is uncertain. RESEARCH QUESTION: Does dietary advice based on routine food allergy tests improve disease control compared with usual care in children with eczema? DESIGN: Pragmatic, multi-centre, parallel group, individually randomised controlled trial (RCT), with internal pilot and nested economic and process evaluation. SETTING: Primary care (84 GP surgeries). PARTICIPANTS: Children (<2 years) with eczema. INCLUSION: Eczema, mild or worse. EXCLUSION: Previous SPT/IgE blood test for, or confirmed IgE-mediated food allergy to, study foods. INTERVENTION: “Good eczema care” leaflet plus dietary advice based on skin prick tests to milk, egg, wheat, and soya, delivered by trained research/practice nurses. COMPARATOR: “Good eczema care” leaflet, to standardise treatment. ALLOCATION: Randomised to intervention or comparator groups (1:1 ratio), stratified by eczema severity and centre. PRIMARY OUTCOME: RECAP (parent completed measures of eczema control) collected four-weekly for 24 weeks. SECONDARY OUTCOMES (over 36 weeks): eczema symptoms (POEM); quality of life (child IDQoL and CHU-9D; parent EQ-5D-5L and Carer QOL); adverse events; dietary variety and primary food groups; weight-for-age and stature-for age; breastfeeding status; parent/carer anxiety (GAD-7). SAMPLE SIZE: 493 children will detect a difference of 1.95 on RECAP between all children in the two treatment groups assuming a standard deviation in RECAP of 6.5, correlation between baseline and 24-weeks of 0.4, 20% loss to follow-up, 90% power and 5% significance level. ANALYSIS: The primary analysis will be performed using a multilevel mixed model framework with observations over time (level 1) nested within participants (level 2). ECONOMIC EVALUATION: The primary perspective will be NHS; 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. PROCESS EVALUATION: In-depth interviews with ~15 GPs; ~15 Research and Practice Nurses; ~30 parents; observation of nurse training sessions; and audio-recording of baseline and intervention group encounters. Quantitative exploration of potential mediators of adherence and intervention outcomes. PATIENT AND PUBLIC INVOLVEMENT: “What role might food allergy tests play in treating eczema?” is a James Lind Alliance research priority. We have surveyed 152 parents, held 6 meetings and 3 public engagement events. We are committed to strong PPI in delivery, with a PPI&E coordinator, co-applicant, TSC member, and advisory group. DISSEMINATION: Our established networks will reach beyond traditional outputs, working with professional bodies in allergy, dermatology, primary care and commissioners to help implement the study’s findings. Uptake will be facilitated by the interest in clinical and lay communities about this issue. PROJECT TIMETABLE: 40 months duration, including 6 months set-up, 29 months recruitment and follow-up, 5 months analysis and reporting.