From the authors

We would like to thank S.S. Cunha and P.J. Newcombe for their discussion of our paper. Although we generally agree with most arguments raised by the two authors, we want to emphasise that their points did not accurately represent our carefully worded statements.

First, using different scenarios, we have shown how estimates of the prevalence of wheeze differ if understanding of the word “wheeze” by parents is taken into account 1. In our paper, table 4 shows that misunderstanding of “wheeze” does not, as often postulated, invariably lead to an overestimate of the prevalence of wheeze, but might also lead to an underestimate as shown for children of south Asian backgrounds and deprived neighbourhoods. We did not claim that “underestimation can be taken as a rule”. The fact that we presented different scenarios, with some showing higher estimates than the observed results and others lower, confirms this. We thank the authors for demonstrating that estimates also depend on baseline prevalence.

Secondly, we agree that risk factors for prevalence are not necessarily risk factors for severity (although they often are). However, we do not agree that severe childhood wheeze can be equated with a poor prognosis and, therefore, that risk factors for severity are the same as risk factors for prognosis. Preschool children with viral-induced wheeze can be very severely ill and hospitalised but still have a good long-term prognosis, as they are likely to grow out of these problems. When we propose to confirm, in a population-based study, important results by a sensitivity analysis “including only those with more severe wheezing” (such as those with more frequent attacks or with disturbed sleep), we think that such a definition would in fact merely exclude those children whose parents have noticed a respiratory noise at some time, and a large proportion of such “more severe” cases would not have even been treated with a bronchodilator 2.

Thirdly, regarding atopy, we have not stated that “presence of atopy is necessary to validate wheeze”. Our wording was to “use objective measurements (such as bronchial responsiveness and allergy tests) to validate findings in subgroups of the population”. We have been well aware of the existence of different phenotypes within the spectrum of wheezing disorders in childhood for many years 3–5. We entirely agree that the presence of atopy is not necessary to diagnose, for instance viral-induced wheeze in young children, but this was not the topic of our paper.