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food_allergy_definition [2022/07/01 14:37]
laura [Table]
food_allergy_definition [2025/02/05 14:49] (current)
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 Researchers from the [[https://​www.rug.nl/​staff/​j.m.vonk/​|University Medical Center Groningen]] developed a definition of food allergy for all Lifelines participants (adults and children) using the [[allergies|allergy variables]] from [[2A]]. ([[sections]]:​ [[Diseases & symptoms]] ([[Allergies]]) and [[secondary & linked variables]]).\\ Researchers from the [[https://​www.rug.nl/​staff/​j.m.vonk/​|University Medical Center Groningen]] developed a definition of food allergy for all Lifelines participants (adults and children) using the [[allergies|allergy variables]] from [[2A]]. ([[sections]]:​ [[Diseases & symptoms]] ([[Allergies]]) and [[secondary & linked variables]]).\\
  
-The Food allergy definition can be requested in the Lifelines catalogue or by mail (data@lifelines.nl).\\+The Food allergy definition can be requested in the [[https://data-catalogue.lifelines.nl/|Lifelines catalogue]].\\
 \\ \\
 ===== Background ===== ===== Background =====
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 \\ \\
 ===== Calculation of food allergy definition ===== ===== 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 [[https://​doi.org/​10.1371/​journal.pone.0231818|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:
 +  * **Criterium 1:** food allergy is only diagnosed by an alternative practitioner
 +  * **Criterium 2:** the onset of symptoms after ingesting the food is after a day or more
 +  * **Criterium 3:** the amount of food that elicits the reaction is a normal portion or more
 +  * **Criterium 4:** the duration of the symptoms is longer than 1 week
 +  * **Criterium 5:** a negative double blind placebo controlled food provocation test
 +\\
 +=== 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 [[https://​doi.org/​10.1371/​journal.pone.0231818|Westerlaken-van Ginkel et al. (2020)]].
  
-=== 1.  ​=== +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: 
 +  - 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. 
 +  - 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 ​=== 
 +  - If a participant has two different questionnaires available, the quetsionnaire with the highest score on food allergy is selected. 
 +  - 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. 
 +  - In the future the type of foods and the type of reactions will be classified and added. 
 +\\
 \\ \\
 ===== Variables ===== ===== Variables =====
food_allergy_definition.1656679051.txt.gz · Last modified: 2025/02/05 14:49 (external edit)