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Reported adverse food reactions overestimate true food allergy in the community
R K Woods1, R M Stoney, J Raven
1Department of Epidemiology and Preventive Medicine, Central and Eastern Clinical School, Monash University and the Alfred Hospital, Australia. Rosalie.Woods@med.monash.edu.au
Objective:
To determine the extent to which perceived adverse food reactions were associated with IgE mediated food allergy, as defined by skin prick testing (SPT).
Design:
A cohort epidemiological study. Participants underwent SPT to five common food allergens (cow's milk, peanut mix, egg white, shrimp and whole grain wheat mix) and were asked whether they had ever suffered any food 'illness/trouble', and if so to list such food(s). A positive SPT was defined as wheal diameter of > or =3 mm. Cohen's kappa (kappa) was used to assess the agreement between SPT and self-reported reactions to food(s) which contained the allergen of interest.
Setting:
Randomly selected adults who took part in the follow-up of the European Community Respiratory Health Survey (ECRHS) in 1998.
Subjects:
The subjects were 457 adults aged 26-50 y.
Results:
Fifty-eight (13%) adults were sensitised to at least one food allergen whilst 99 adults (22%) reported illness to food(s) nearly always. However, only seven subjects who reported illness to a food also had a positive SPT to the same food. The prevalence of adverse food reactions associated with IgE mediated allergy in the adult general population would be less than 1.5% (7/457). The agreement between SPT and self-reported illness to food(s) was poor for cow's milk (kappa=0) and wheat (kappa=0), slight for shrimp (kappa=0.16) and egg white (kappa=0.09) and fair for peanut mix (kappa=0.37).
Conclusions:
There was little agreement between self-reported perceived illness to food(s) known to contain the food allergen of interest, and positive SPT, suggesting that most reactions are not due to IgE mediated food allergy.