Socioeconomic deprivation and asthma prevalence and severity in young adolescents.

This study used the international study of asthma and allergies in childhood (ISAAC) to investigate the association between asthma and socioeconomic deprivation among young adolescents in Cape Town, South Africa. The completed ISAAC written and video questionnaires of 4,706 13-14-yr-old school pupils were used. The prevalence of asthma symptoms was analysed by a local index of socioeconomic deprivation, based on residential location and defined on a 10-category scale from least to most deprived. Linear trends were examined visually and the prevalence odds ratio was used to summarize overall trends. In general, the least socioeconomically deprived pupils reported higher prevalences of asthma symptoms "ever" and "in the last 12 months". In contrast, the most socioeconomically deprived pupils reported higher asthma-symptom occurrence monthly or more frequently in the previous 12 months. A subgroup of pupils from low-income areas commuting to better-off schools showed the highest symptom prevalences. The findings are consistent with a model in which an increase in the incidence of asthma is driven by factors associated with improved social circumstances, whereas severity is determined by factors associated with poverty. The impact of social mobility on asthma, including reporting of symptoms, deserves closer study.