Follow up of LEAP Participants and Their Families

This prospective, cross-sectional study was designed to improve understanding of how early-life introduction of peanuts may promote the maintenance of tolerance in adolescence and will serve as an additional safety evaluation of the original nutritional intervention.

Background: Food allergies and specifically peanut allergy (PA) are increasingly common conditions and are an important public health concern. Dietary avoidance of peanut in early life has been recommended in many countries. However, there is evidence that the prevalence of PA is decreased in countries where children are fed peanut beginning at an early age.

The LEAP (Learning Early About Peanut allergy) Study (Protocol ITN032AD, NCT00329784) demonstrated that the early consumption of peanut in high-risk infants successfully reduced the prevalence of peanut allergy at five years of age when compared to peanut avoidance. The LEAP-On Study (Protocol ITN049AD, NCT01366846) was a follow-on study to LEAP and demonstrated that children who consumed peanut in the LEAP study remained protected against developing peanut allergy after cessation of peanut consumption for a period of 12 months.

This LEAP Trio cohort study, a longer-term follow-up of the LEAP study participants, assessed whether the benefits of regular early-life peanut consumption are maintained over many years when peanut consumption is ad libitum (in the amount and frequency chosen by the individual participant).

The three cohorts in LEAP-Trio include:

* LEAP Participants (NCT00329784, NCT01366846)
* their Siblings and
* their Parents

The study began on July 5, 2018, with data collection continuing until August 31, 2022. This allowed for the enrollment of former LEAP participants aged 12 years.:

• The enrollment phase was 217 weeks (4 years, 2 months).

--The LEAP siblings and parents were enrolled concurrently with the LEAP participant.

• Study participation was defined as a single visit (Visit 144 months); however, more than one clinic appointment might have been required to complete all assessments and were required to be completed within 8 weeks of the in-person visit. Due to COVID-19, telephone visits were undertaken when participants were not able to or did not wish to come into the clinic or have a home visit. The visit window did not apply to the telephone visit. Participants who underwent a telephone visit were invited to subsequently undergo an in-person clinic visit or home visit.

Participant assessments included general medical, -dietary, -allergy (including but not limited to oral peanut food challenges for former LEAP participants and their siblings), and mechanistic assessments (involving the collection of biological specimens, a blood draw, skin prick testing, as examples, to explore hypotheses related to potential mechanisms of peanut allergy).

Eligibility Criteria:
Inclusion Criteria:

Inclusion Criteria - LEAP Participants:

* Participation in LEAP;
* At least 9.5 years of age
* Willingness to participate in at least one study data collection (i.e. questionnaire, skin pricking testing, or blood draw) procedure; and
* Assent by child and informed consent by parent or legal guardian.

Inclusion Criteria - LEAP Siblings:

* Sibling of LEAP participant;
* Willingness to participate in at least one study data collection (i.e. questionnaire, skin pricking testing, or blood draw); and
* Assent by child and informed consent by parent or legal guardian if child is younger than 16; siblings aged 16 and over will provide their own consent.

Inclusion Criteria - LEAP Parents:

* Biological parent of LEAP participant;
* Willingness to participate in at least one study data collection (i.e. questionnaire, skin pricking testing, or blood draw); and
* Informed consent (for participants only returning a Questionnaire, informed consent will be implied).

Exclusion Criteria:

* There are no exclusion criteria for LEAP Participants, LEAP Siblings, LEAP Parents