The social determinants of asthma

In all communities, poverty is strongly related to ill health 1. This has not generally been the pattern for asthma, where the lifetime prevalence of symptoms is usually higher in more affluent societies 2, 3, and a rising prevalence of asthma is a price paid for increasing national prosperity. This trend is probably inevitable since to date, no public health strategy for large-scale primary prevention of asthma has yet proved feasible or effective. The favoured reason for this apparent protective effect of low socioeconomic status (SES) and/or of a rural lifestyle for atopy and asthma is the hygiene hypothesis, which, in its simplest form, suggests that early life exposure to microbial products modulates the immune response away from mechanisms related to the development of atopy 4, 5. In recent years, data from many studies have challenged this view 6. There have been consistent demonstrations of a positive association between lower SES and risk of wheezing in children and adolescents, both in high- and low/middle-income countries (LMICs), indicating a more complex interaction between factors, some protective and others causative. While dichotomising society into either “hygienic” and “unhygienic” is appealing, it is an obvious oversimplification of the environment in which we all live. More importantly, for healthcare planners, all communities are at risk of rapid change in the prevalence of asthma as living conditions change, and the largest increases are being observed in some LMICs with large populations 3. This represents a burden for which they are often ill-equipped. However, on more detailed review, the association between poverty and asthma prevalence is not fully understood and deserves further investigation. First of all a distinction must be made between risk of asthma ever (lifetime risk) and current symptoms 2. Gross national product per capita is …