Occurrence of parent-reported food hypersensitivities and food allergies among children aged 1-4 yr

Real-life epidemiology of food allergy testing in Finnish children

BACKGROUND

The cumulative incidence of parental-reported symptoms of food allergy (FA) during the first years of life is estimated to exceed 30%. However, the occurrence and determinants of FA testing in a general child population have remained unknown.

METHODS

The study population comprised all 5920 children aged 0-4 yr in the province of South Karelia, Finland, identified from the nationwide population register. The study included a questionnaire survey and a retrospective collection of FA test results (skin prick tests, IgE antibodies, or open food challenges) from the patient records of the entire study population. The questionnaire and patient record data were linked together on an individual basis with the parents' permission.

RESULTS

A total of 5849 FA tests had been performed on 961 children. By the age of 4 yr, the cumulative incidence of FA testing was 18% for any food item; 17% for essential items (milk, egg, cereals) and 9% for other food items. Essential food items had been tested in 90% of children who reportedly had a physician-diagnosed FA for these. The incidence of testing was 30% higher in boys than in girls and twofold higher among the offspring whose either or both parents reportedly had some allergic manifestation.

CONCLUSIONS

A large proportion of children are subjected to FA testing in their early years. This result shows the need to evaluate the financial burden of FA testing and to improve current testing practices.

Heredity of food allergies in an unselected child population: an epidemiological survey from Finland

The heredity of food allergies (FA) has not previously been addressed in a large unselected child population. Our target population comprised all children born from April 2001 to March 2006 resident in one province of South-East Finland (n c. 6000), as identified from the national population register. In a questionnaire survey conducted in 2005-2006, data were obtained on allergic manifestations (FA symptoms, atopic rash, allergic asthma, hay fever/pollen allergy, or animal allergy) in the biologic parents of 3800 children (64% of the total). Concurrently with the survey but independently of it, results of specific immunoglobulin E antibodies (sIgE), skin prick tests (SPT), and open food challenges (OFC) in the offspring were collected from patient records throughout the province. Up to the age of 4 yr, the incidences of any positive FA test, a positive SPT or sIgE for food items, and a positive OFC in these children were threefold higher if both parents reported having an allergic manifestation and twofold higher if either mother or father had such a manifestation when compared with children whose parents did not report any of these conditions. The estimated risk of any positive FA test increased by a factor of 1.3 (95% CI 1.2-1.4) for each additional allergic manifestation in the parents. Positive FA tests in the offspring were relatively strongly associated with the reports of allergic phenotypes and the number of these phenotypes in their biologic parents.

SKARP - A population-based cohort study of childhood food-associated symptoms perceived by parents and food allergies diagnosed by physicians: Design, methods and participation

Background: Few epidemiological studies exist on food-associated symptoms and allergies in large unselected child populations. Aims: To describe the design, methods and participation rate of the South Karelian Allergy Research Project (SKARP), a population-based epidemiological study on food-associated symptoms and physician-diagnosed food allergies. Methods: The study population of 5,973 children born between 2001 and 2006 and resident in the province of South Karelia, Finland, was identified from the nationwide population register. The parents received a questionnaire to be returned at their child’s annual visit to the child health clinic, where supplementary interviews were performed. Results of allergy tests (skin prick tests, immunoglobulin E antibodies and open food challenges) performed on participants and non-participants were collected from the relevant health care units in the area. Results: Participation rates in the questionnaire study were 54% (644/1,194) among the parents of neonates and 69% (3308/4,779) among those of the children aged 1 to 4 years. Cooperation with the child health clinics and mailing of a reminder questionnaire improved participation by 8 and 10 percentage points, respectively. The final participation rate seemed to be unaffected by whether the child had or had not been tested for suspected allergy. Conclusions: A reasonably good participation rate and almost complete coverage of allergy tests were achieved thanks to successful cooperation with the child health clinics and test laboratories. This baseline study forms a representative database to estimate the occurrence of food-associated symptoms, physician-diagnosed food allergies and allergy testing in the general population.