Early intervention in childhood asthma

The supplement which accompanies this edition of the Journal explores the methodological issues which face all those who are interested in the subject of early intervention in childhood asthma (and other wheezing disorders) [1]. This has become a topical issue as evidence has increased that a number of factors which can affect the development of the foetus and young child may determine respiratory health for the rest of an individual's lifetime. Interventions early in childhood or early in the course of the disease itself can have a number of objectives. It may be important to distinguish these in considering the development of intervention programmes. Their pragmatic value is of course in their potential to reduce morbidity both for individuals and, of course, for populations. However, the theoretical basis for many interventions is weak. Another purpose is therefore to improve our understanding of important disease processes in asthma by examining the outcome of controlled interventions in groups of subjects. Clinical research always contains an element of conflict between these two approaches, since it is natural for those involved in patient-care to wish to find the solution to the health-needs of their patients as quickly as possible, even if this sometimes means bypassing the more laborious aspects of scientific research into the mechanisms of disease. However, by means of carefully designed studies, both decreased morbidity and improved scientific knowledge can be achieved. While the distinction between primary and secondary