Table of Contents

Food allergy definition

Researchers from the University Medical Center Groningen developed a definition of food allergy for all Lifelines participants (adults and children) using the allergy variables from 2A. (sections: Diseases & symptoms (Allergies) and secondary & linked variables).

The Food allergy definition can be requested in the Lifelines catalogue.

Background

In 2020, Westerlaken-van Ginkel et al. published a paper in which an algorithm to define food allergy in adults in Lifelines is developed and described. Since the allergy variables for adults differ slightly from those of children (completed by the parents) and adolescents, this algorithm has to be adapted to defined food allergy in children/adolescents as well.


Calculation of food allergy definition

The calculation of the food allergy definition consisted of three steps: 1) coding of open text variables, 2) defining and calculating criteria to define food allergy, and 3) creating the overall food allergy variables.

1. Coding of open text variables

At the start of the process, the responses from participants on “other allergen”, “other reaction”, and “other person who diagnosed the food allergy” are coded. The allergens and reactions were coded as common, less common, and uncommon using the tables as descibed by Westerlaken-van Ginkel et al. (2020). These original coding tables were slightly changed after reachging consensus. The “other person” items have been coded into alternative practitioner, other person, and no person mentioned.

2. Defining and calculating criteria to define food allergy

For adults, five criteria are included in the questionnaire, where the answers to these should not fall in the unlikely category. The unlikely answers are:


3. Creating overall food allergy variables

Food allergy was coded as no food allergy (0), indeterminate food allergy (1), and likely food allergy (2) according to the flow diagram provided in the paper of Westerlaken-van Ginkel et al. (2020).

For children and adolescents only the two criteria have been asked. As a result, the food allergy definition is based on these two criteria only.For adults, it was decided to include two additional definitions of food allergy:

  1. A version without incorporating criterium 3 as there were many participants who reported a likely allergen and a likely reaction while the other four criteria were not unlikely.
  2. A version including only criterium 1 and 2, to make the definition comparable to the one for children and adolescents.


Remarks from the UMCG researchers

  1. If a participant has two different questionnaires available, the quetsionnaire with the highest score on food allergy is selected.
  2. If a researcher wants to investigate food allergy in both children/adolescents and adults it is recommended to use foodallergy_score_all_c_1. If a researcher wants to investigate food allergy in adults only, it is recommended to use foodallergy_score_adu_c_2 and use the foodallergy_score_adu_c_3 variable in a sensitivity analysis.
  3. In the future the type of foods and the type of reactions will be classified and added.



Variables

Label English Label Dutch Code Variable Assessment Age
age at definition of food allergy (based on questionnaire) leeftijd ten tijde van definitie voedselallergie (op basis van moment vragenlijst) foodallergy_age_all_c_1 agefa sec * all
reported product is likely allergenic? gerapporteerd product is waarschijnlijk allergeen? foodallergy_allergen_ach_c_1 likelyallergen_ach sec * all
reported product is likely allergenic? gerapporteerd product is waarschijnlijk allergeen? foodallergy_allergen_adu_c_1 likelyallergen_adu sec * all
reported product is likely allergenic? gerapporteerd product is waarschijnlijk allergeen? foodallergy_allergen_chi_c_1 likelyallergen_chi sec * all
reported reaction is likely allergic? gerapporteerde reactie is waarschijnlijk allergisch? foodallergy_reaction_ach_c_1 likelyreaction_ach sec * all
reported reaction is likely allergic? gerapporteerde reactie is waarschijnlijk allergisch? foodallergy_reaction_adu_c_1 likelyreaction_adu sec * all
reported reaction is likely allergic? gerapporteerde reactie is waarschijnlijk allergisch? foodallergy_reaction_chi_c_1 likelyreaction_chi sec * all
presence of food allergy according to criteria 1 and 2 (excluding criteria 3: amount of food eliciting reaction, 4: duration of symptoms, and 5: result dbpcfc) aanwezigheid van voedselallergie volgens criteria 1 en 2 (exclusief criteria 3: hoeveelheid voedsel dat reactie uitlokt, 4: duur van symptomen, en 5: resultaat dbpcfc) foodallergy_score_ach_c_1 foodallergy_ach sec * all
presence of food allergy according to criteria 1 and 2 (excluding criteria 3: amount of food eliciting reaction, 4: duration of symptoms, and 5: result dbpcfc) aanwezigheid van voedselallergie volgens criteria 1 en 2 (exclusief criteria 3: hoeveelheid voedsel dat reactie uitlokt, 4: duur van symptomen, en 5: resultaat dbpcfc) foodallergy_score_adu_c_1 foodallergy3_adu sec * all
presence of food allergy according to criteria 1, 2, 4, and 5 (excluding criteria 3: amount of food eliciting reaction) aanwezigheid van voedselallergie volgens criteria 1, 2, 4, en 5 (exclusief criteria 3: hoeveelheid voedsel dat reactie uitlokt) foodallergy_score_adu_c_2 foodallergy2_adu sec * all
presence of food allergy according to criteria 1, 2, 3, 4, and 5 aanwezigheid van voedselallergie volgens criteria 1, 2, 3, 4, en 5 foodallergy_score_adu_c_3 foodallergy_adu sec * all
presence of food allergy based on [foodallergy_score_adu_1] and [foodallergy_score_ach/chi_c_1], with the highest score shown in case of multiple scores per participant aanwezigheid van voedselallergie gebaseerd op [foodallergy_score_adu_1] en [foodallergy_score_ach/chi_c_1], met de hoogste score weergegeven in het geval van meerdere scores per deelnemer foodallergy_score_all_c_1 fa3 sec * all
presence of food allergy based on [foodallergy_score_adu_2] and [foodallergy_score_ach/chi_c_1], with the highest score shown in case of multiple scores per participant aanwezigheid van voedselallergie gebaseerd op [foodallergy_score_adu_2] en [foodallergy_score_ach/chi_c_1], met de hoogste score weergegeven in het geval van meerdere scores per deelnemer foodallergy_score_all_c_2 fa2 sec * all
presence of food allergy based on [foodallergy_score_adu_3] and [foodallergy_score_ach/chi_c_1], with the highest score shown in case of multiple scores per participant aanwezigheid van voedselallergie gebaseerd op [foodallergy_score_adu_3] en [foodallergy_score_ach/chi_c_1], met de hoogste score weergegeven in het geval van meerdere scores per deelnemer foodallergy_score_all_c_3 fa sec * all
presence of food allergy according to criteria 1 and 2 (excluding criteria 3: amount of food eliciting reaction, 4: duration of symptoms, and 5: result dbpcfc) aanwezigheid van voedselallergie volgens criteria 1 en 2 (exclusief criteria 3: hoeveelheid voedsel dat reactie uitlokt, 4: duur van symptomen, en 5: resultaat dbpcfc) foodallergy_score_chi_c_1 foodallergy_chi sec * all

* The food allergy definition variables are included as assessment 'sec' because they link to different questionnaires from assessment 2A.