Association of early life wheeze and lung function.

BACKGROUND

The incidence of wheeze is unknown and the role of early life wheeze in subsequent health is not clearly understood.

OBJECTIVE

To calculate the age-specific incidence of wheeze and determine whether wheezing at particular times in early life was predictive of abnormal airway hyperresponsiveness (AHR), percentage of predicted forced expiratory volume in 1 second (FEV1), and current asthma at the age of 6 years.

METHODS

Using data from a birth cohort study with annual report of wheezing (Childhood Allergy Study) and spirometry and methacholine challenge at the age of 6 years, the age-specific incidence of wheeze was determined using Kaplan-Meier estimates. Logistic and linear regression models were used to assess the associations between the presence of age-specific wheezing and the outcomes of current asthma, AHR, and percentage of predicted FEV1 at the age of 6 years.

RESULTS

A total of 724 children had parents who completed at least the first annual interview and were therefore included in the study. The 6-year cumulative incidence of wheezing was higher for boys (66.2%; 95% confidence interval, 59.8%- 72.6%) than for girls (47.6%; 95% confidence interval, 41.4%-53.8%). There was no age when wheezing was more strongly associated with either AHR or percentage of predicted FEV1 at 6 years. Only wheeze in the fifth year among boys and wheezing in both the fourth and fifth years in girls were positively predictive of current asthma at the age of 6 years. This is likely because of the definition of current asthma (ever physician diagnosis and either medication or symptoms in last year). Eczema, parental asthma history, and total cord blood IgE did not affect these associations.

CONCLUSIONS

Wheezing at any particular time in early life may not be predictive of early childhood lung function.