Wheeze in preschool children
Authors: George Russell
Journal: BMJ (2008)

Wheeze is an increasingly common symptom in preschool children. In Leicestershire, the proportion of children aged less than 5 years who had ever wheezed rose from 16% in 1990 to 29% in 1998.1 Wheezing illness is therefore a common source of anxiety to parents and professionals involved in the care of young children, all of whom would like an accurate diagnosis and prognosis. In the accompanying study, Frank and colleagues report the long term outcome of 628 children with and without preschool wheeze, including factors that predict asthma in later life.2

Many different wheeze phenotypes have been described in this age group.3 4 Most children will eventually turn out to have been “transient early wheezers.” These children do not usually have a family history or personal history of atopy, and the wheeze tends to settle by the age of 3 years. A second group of children with transient symptoms consists of “non-atopic wheezers,” most of whom settle by the age of 5 years, although the syndrome can persist well into school age years (figure​(figure).5



Prevalence of wheeze phenotypes in childhood; these groups are by no means mutually exclusive, and considerable overlap occurs. Adapted, with permission, from Stein et al4



These two groups overlap considerably; infection is the main precipitant of wheeze in both, so they are often lumped together as having “virus associated wheeze” or “wheezy bronchitis.” These two groups can be distinguished by pulmonary function measurements—the transient early wheezers have relatively narrow airways that are readily obstructed by the minor degree of mucosal inflammation that accompanies upper respiratory tract infection, whereas the non-atopic wheezers show bronchial hyper-reactivity to methacholine.4 These assessments are unlikely to be available to clinicians working outside tertiary centres, however.

A third group—“IgE associated wheeze”—is important because wheeze tends to persist in these children and a diagnosis of asthma can reasonably be offered. It is defined in terms of objective measures of atopy—that is, raised IgE concentrations, positive radioallergosorbent tests, or positive skin prick tests.4 This type of wheeze is also associated with evidence of airway inflammation in the form of raised exhaled nitric oxide concentrations.6

Faced with a wheezing toddler or infant, what should clinicians do? Firstly, it must be established that wheeze is actually present. The public’s understanding of the term wheeze seems to have changed. This term should be reserved for whistling noises, but it is now being used to describe various vibratory phenomena.7 Mindful of these problems, in a birth cohort study in Aberdeen, we identified 210 parents who described their 2 year old children as having wheezed; of these, only 24 (11%) defined this wheeze as whistling in character, the others described it as a rattling or purring noise.8 Parental use of the word wheeze must therefore be viewed with suspicion.

Parents will have little interest in the taxonomy of wheezing disorders but will want to know about treatment and prognosis. In terms of treatment, the efficacy of β2 agonists during infancy is still unclear,9 but they are generally effective in older children, particularly if given by means of a holding chamber (spacer) and mask.10 Inhaled corticosteroids are of little benefit in intermittent virus associated wheeze and are best reserved for children with more frequent or severe symptoms, particularly if there is a personal or family history of other atopic disorders, positive skin prick tests, or biochemical evidence of atopy.11 12

Until now it has been difficult to provide prognostic information on individual children, but Frank and colleagues’ study helps by assessing the predictive value of simple clinical data rather than complex immunological and physiological tests.2 The authors examined several factors that might influence the prognosis of wheeze in early childhood. Surprisingly, the severity and frequency of symptoms were unrelated to the persistence of symptoms. In contrast, a history of exercise induced wheeze—a clinical manifestation of bronchial hyper-reactivity—and a history of atopic disorders strongly predicted persistence (exercise: odds ratio 4.44, 95% confidence interval 1.94 to 10.13; atopy: 3.94, 1.72 to 9.00). These findings support the traditional view that asthma is essentially the occurrence of these two traits in the same person.

Obviously, it could be argued that these results are exactly what might have been anticipated—the more it looks like asthma, the more likely it is to be asthma—but most clinicians would probably have expected the frequency and severity of attacks to have had some bearing on prognosis. This study therefore provides the clinician with a simple approach to prognosis in the wheezy preschool child using information that is easily acquired at the bedside or in the consulting room. Nevertheless, the confidence intervals surrounding these adjusted odds ratios are quite wide (and in the case of male sex include unity), so the approach should be used as a guide rather than a formula for certainty.