Asthma symptoms and medication in the PIAMA birth cohort: evidence for under and overtreatment.

OBJECTIVE: Under and overtreatment of asthma may be a serious problem especially in young children, but the evidence is scarce and no longitudinal data are available. Our aim was to investigate whether inhaled medication use in young children was in agreement with asthma symptoms at the age of 2-8 yr. METHODS: Data were used from the 'Prevention and Incidence of Asthma and Mite Allergy' birth cohort, consisting of 3963 children born in the Netherlands. Between age 2 and 8 yr, children were followed up using annual postal questionnaires. Age-specific prevalences of asthma symptoms were assessed and compared with reported use of inhaled bronchodilators and/or corticosteroids. RESULTS: The proportion of current wheeze decreased with age. About a third of 'current wheezers' did not use any inhaled medication during the years in which symptoms were reported. At 8 yr, 30% of children with reported 'severe current asthma symptoms' were not using inhaled corticosteroids. On the other hand, up to 50% of children with inhaled corticosteroids for at least 2 yr did not report any wheezing during those 2 yr. CONCLUSION: The proportion of symptomatic children without appropriate treatment was substantial throughout childhood, even when parents reported prolonged or severe symptoms. Treatment of asymptomatic children with inhaled corticosteroids increased with age and accounted for up to a third of all inhaled steroid use at 8 yr. These findings suggest that under and overtreatment of asthma in children was common.