Persistence of Oral Tolerance to Peanut (LEAP-On)

• Number of Participants With Peanut Allergy (PA) at 72 Months of Age - by Skin Prick Test Stratum [ Time Frame: 72 months ]
  At 72 months of age, eligible participants were given an oral food challenge (oral intake of 5g of peanut protein in a single dose). Participants were considered to not have peanut allergy (PA) if they experienced no reaction following the food challenge. Those who did react were offered a double-blind, placebo-controlled food challenge with a total of 13.7g of peanut protein administered in increments. These participants were considered to have PA if they experienced a reaction at any point during the dose escalation. For participants for whom data from the oral food challenge were either inconclusive or not available, a diagnostic algorithm based on the results of a SPT and the values for peanut-specific IgE were used to determine whether or not a participant should be considered to have PA.
  
  
• Number of Participants With Peanut Allergy (PA) at 72 Months of Age - by Treatment Group [ Time Frame: 72 months ]
  At 72 months of age, eligible participants were given an oral food challenge (oral intake of 5g of peanut protein in a single dose). Participants were considered to have no peanut allergy (PA) if they experienced no reaction following the food challenge. Those who did react were offered a double-blind, placebo-controlled food challenge with a total of 13.7g of peanut protein administered in increments. These participants were considered to have PA if they experienced a reaction at any point during the dose escalation. For participants for whom data from the oral food challenge were either inconclusive or not available, a diagnostic algorithm based on the results of a SPT and the values for peanut-specific IgE were used to determine whether or not a participant should be considered to have PA.
  
  
• Number of Participants With Peanut Allergy (PA) at 72 Months of Age - by Skin Prick Test Stratum in the Per Protocol Population [ Time Frame: 72 months ]
  At 72 months of age, eligible participants were given an oral food challenge (oral intake of 5g of peanut protein in a single dose Participants were considered to have no peanut allergy (PA) if they experienced no reaction following the food challenge. Those who did react were offered a double-blind, placebo-controlled food challenge with a total of 13.7g of peanut protein administered in increments. These participants were considered to have PA if they experienced a reaction at any point during the dose escalation. For participants for whom data from the oral food challenge were either inconclusive or not available, a diagnostic algorithm based on the results of a SPT and the values for peanut-specific IgE were used to determine whether or not a participant should be considered to have peanut allergy.
  
  
• Number of Participants With Peanut Allergy (PA) at 72 Months of Age - by Treatment Group in the Per Protocol Population [ Time Frame: 72 months ]
  At 72 months of age, eligible participants were given an oral food challenge (oral intake of 5g of peanut protein in a single dose Participants were considered to have no peanut allergy (PA) if they experienced no reaction following the food challenge. Those who did react were offered a double-blind, placebo-controlled food challenge with a total of 13.7g of peanut protein administered in increments. These participants were to have PA if they experienced a reaction at any point during the dose escalation. For participants for whom data from the oral food challenge were either inconclusive or not available, a diagnostic algorithm based on the results of a SPT and the values for peanut-specific IgE were used to determine whether or not a participant should be considered to have PA.
  
  

• Number of Participants With Peanut Allergy (PA) at 60- and 72-month Visits Within the Peanut Avoidance After Peanut Consumption Group [ Time Frame: 60 months and 72 months ]
  At 60 and 72 months of age, eligible participants were given an oral food challenge (intake of 5g of peanut protein in a single dose). Participants were considered to have no peanut allergy (PA) if they experienced no reaction following the food challenge. Those who did react were offered a double-blind, placebo-controlled food challenge with a total of 9.4g/13.7g (month 60/month 72) of peanut protein administered in increments. These participants were considered to have PA if they experienced a reaction at any point during the dose escalation. For participants for whom data from the oral food challenge were either inconclusive or not available, a diagnostic algorithm based on the results of a SPT and the values for peanut-specific IgE were used to determine whether or not a participant should be considered to have PA.
  
  
• Number of Peanut Avoidance After Peanut Consumption Group Participants With Peanut Allergy (PA) at 60- and 72-month Visits Within in the Per Protocol Population [ Time Frame: 60 months and 72 months ]
  At 60 and 72 months of age, eligible participants were given an oral food challenge (intake of 5g of peanut protein in a single dose). Participants were considered to have no peanut allergy (PA) if they experienced no reaction following the food challenge. Those who did react were offered a double-blind, placebo-controlled food challenge with a total of 9.4g/13.7g (month 60/month 72) of peanut protein administered in increments. These participants were considered to have PA if they experienced a reaction at any point during the dose escalation. For participants for whom data from the oral food challenge were either inconclusive or not available, a diagnostic algorithm based on the results of a SPT and the values for peanut-specific IgE were used to determine whether or not a participant should be considered to have PA.
  
  

This is a two-sample comparison employing all available study participants in both arms of the LEAP (NCT00329784) study at visit 72. After obtaining informed consent, LEAP participants who are evaluable for peanut allergy at age 60 months (V60) will be enrolled into this study, the LEAP-On (NCT01366846) Study. All LEAP-On participants will avoid peanut for an additional 12 months regardless of their previous allocation to the LEAP Study consumption arm (Group A) or the LEAP Study avoidance arm (Group B).

At V72, after 12 months of this new intervention, all participants will have skin prick testing (SPT), specific IgE and a repeat oral challenge to peanut to determine the frequency of peanut allergy in both groups. The LEAP Study decision table will be used to determine the presence of peanut allergy. Briefly, peanut allergy will be based on the presence of a positive oral peanut challenge with objective signs of allergy. Tolerance will be established on the basis of a negative oral peanut challenge (tolerating 5 g of peanut protein in the absence of symptoms). For participants who do not have an oral challenge or an oral challenge at V72 with a determinate outcome, the following criteria will be used to determine their outcome at V72:

• If the participant is tolerant and has an IgE > 0.1 and/or SPT > 0 mm at V60, the participant will be considered non-evaluable and will not be included in the analysis.
• For all other participants, the V60 outcome will be applied to the V72 outcome (last observation carried forward).

Predictive values of peanut-specific IgE and/or SPT will not be used in the LEAP-On study because participants in the peanut consumption arm in the LEAP study are tolerating peanuts despite having high IgE and/or SPT.