Sample size calculation
Based on data from the HealthNuts study [2] it is assumed that 36% of children with peanut allergy will have a tree nut allergy at age 18 months of age. A sample size of 95 per arm will provide 80% power to detect a relative reduction of 50% or greater (to 18% in the multi-nut OFC group) based on a 2-sided chi-squared test with no continuity correction. To allow for 10% loss to follow-up we require a total of 212 infants, 106 per arm.
Families may withdraw their involvement in the trial at any time, without explanation and without implications to their future care. Where possible, the reason for withdrawal will be recorded. Participants who discontinue or are withdrawn will not be replaced.