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.