Low income as a protective factor against asthma in children and adolescents treated via the Brazilian Unified Health System.

OBJECTIVE To analyze the role that low income plays in the development of asthma in children and adolescents. METHODS A case-control study using a questionnaire. RESULTS A total of 687 participants were studied at a tertiary hospital via the Brazilian Unified Health System. Ages ranged from 5 to 15 years, and 54.7% of the participants were male. Nearly half of the individuals (49.1%) lived in the metropolitan area of the city of Recife, and the remainder lived in the countryside. Most (98.1%) lived in concrete houses or apartments, with a mean of 5.7 rooms and 4.8 occupants per residence. Mean maternal level of education was 6.8 years of schooling. The median monthly per capita income was R$ 103.75 (Brazilian reals). The sample was stratified according to cut-off points related to the national minimum wage (R$350.00): <25% of minimum wage = very low income (39% of the sample); <50% of minimum wage = low income (37.3% of the sample); and > or =50% of minimum wage = satisfactory income (23.7% of the sample). There was no association between poverty and development of asthma. CONCLUSIONS Poverty is not protective against asthma in children and adolescents treated via the Brazilian Unified Health System, as we might suppose based on the hygiene hypothesis. However, cohort studies are needed in order to confirm these findings.