Predicting the long-term outcome of preschool wheeze: Are we there yet?

Abstract

Asthma is one of the more difficult diagnoses for doctors to make in the preschool age group. Wheeze as a symptom is often inaccurately reported by parents, and many children with wheeze have diagnoses other than asthma. In this month’s issue of the Journal, Caudri et al present a clinical risk score to improve the diagnosis of asthma in preschool children. They have used data from the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) birth cohort, in which participants were assessed on a yearly basis to the age of 8 years. The cohort study enrolled 3963 children and has achieved excellent follow-up rates, with 80% of the eligible study population providing data at 8 years of age. In the subgroup of children who reported wheeze or coughing at night without a cold until age 4 years, they assessed possible predictors for asthma at 7 to 8 years of age. They found that male sex, postterm delivery, parental education, inhaled medication, wheezing frequency, wheeze/dyspnea apart from colds, respiratory infections, and eczema all independently predicted later asthma. One of the challenges of asthma research is the absence of a gold standard diagnostic test. The authors have defined asthma on the basis of wheeze, the prescription of inhaled corticosteroids, or a doctor’s diagnosis of asthma during each of the seventh and eighth years of life. This definition does lead to the potential for misclassification bias, resulting in overdiagnosis of asthma, because parents are very poor at accurately reporting wheeze. Given that only 10% of children with asthma were diagnosed just on the basis of reported wheeze, any bias should be minimal. Over the last decade, a number of asthma predictive scores have been put forward. The authors compare and contrast their score with the predictive index of Castro-Rodriguez et al. This was developed in a much smaller birth cohort with a very different ethnic mix. Castro-Rodriguez et al included eosinophilia as a minor criterion, although a complete blood count is not generally part of the work up of a preschool child presenting wheeze. By using more predictive factors, Caudri et al seem to have generated a more accurate predictive score with their chosen cut-off levels. A