Allergy from infancy to adolescence. A population-based 18-year follow-up cohort.

Background: Anxious parents have many concerns about the future health of their atopic infants. Paediatricians and primary care practitioners need to seek knowledge on long-term outcomes in order to cope with the increasing caseload of suspected allergy and the concerns of parents. The aim of the study was to assess suspected and diagnosed allergy in infancy as predictors of allergy and asthma in adolescence.

Methods: Families expecting their first baby and making their first visit to a maternity health care clinic in 1986 were selected as the study population in a random sample. There were 1278 eligible study families. The data were provided of the children at the ages of 9 and 18 months and 3, 5, 12, 15 and 18 years by health care professionals, parents, and adolescents (themselves).

Results: At the age of 9 months, the prevalence of allergy suspicions was distinctly higher than that of allergy diagnoses. At the age of five years suspected allergy approaches were nil, and the prevalence of diagnosed allergy was about 9%. During the adolescence, the prevalence of self-reported allergy increases steadily up to the age of 18 years, and that of asthma remains at approximately 5%. Suspected allergy at the age of 9 or 18 months and at the 5 years of age does not predict allergy at adolescence. Compared with non-allergic children, children with definite allergy at the age of 5 were over 8 times more likely to have allergy and nearly 7 times more likely to have asthma in adolescence.

Conclusion: An early ascertained diagnosis of allergy, but not suspicions of allergy, predicts prevailing allergy in adolescence. Efforts need to be focused on accurate diagnosis of early childhood allergies.