Wheeze and asthma in developing countries

S tandardised population based health surveys have produced much useful information on the prevalence and determinants of asthma in children (International Study of Asthma and Allergy in Children (ISAAC) study) and adults (European Community Respiratory Health Study (ECRHS) study). Most sites participating in these studies have been in high income countries and, because some centres took part at their own expense, the populations studied were probably not representative of their countries as a whole. In addition, a number of national health surveys such the US National Health and Nutrition Survey (NHANES), the Canadian National Health Survey, and National Birth Cohort Studies (UK, New Zealand) 6 have been conducted, all in high income countries. In this issue of Thorax Ehrlich et al, in what is one of the first such studies in a developing (in this case middle income) country, describe the results of a national health survey conducted among 13 826 South Africans aged 15 years and over to determine the national prevalence and predictors of three outcomes: (1) wheezing symptoms, (2) an asthma diagnosis, and (3) use of asthma medication. This was an ambitious undertaking (and a remarkably successful one) given the racial, linguistic, and socioeconomic heterogeneity of the population and its quadruple burden of HIV, other infections (including tuberculosis), chronic noncommunicable disease, and injury. What is surprising is not that the findings in this paper and in its companion paper on chronic bronchitis were different from those published for developed (high income) countries, but that in how many respects they were similar.