Environmental Risk Factors in the First Year of Life and Childhood Asthma in the Central South of Chile

Abstract

Background. Childhood asthma has a high prevalence in South America—a region of the world currently undergoing a thorough modernization and transition process. Asthma in South America is mainly associated with poor urban environment, which actually may challenge the role of the hygiene hypothesis. We systematically assessed the impact of environmental factors in the first year of life on asthma. Methods. A case–control study including 188 asthmatics and 294 hospital-based controls aged 6–15 years was carried out in the Central South of Chile. Parents of study participants completed a computer-assisted interview on environmental factors (such as birth order, day-care attendance, pneumonia infection, regular animal and furry pet contact, and environmental tobacco smoke exposure) in the first year of life and potential confounders. Atopy was assessed using skin prick tests. Multivariate logistic regression models were calculated to assess the association between exposures and asthma, adjusting for potential confounders. Results. Day-care attendance (OR = 0.31; 95% CI: 0.10, 0.94) and regular farm animal contact (OR = 0.38; 95% CI: 0.17, 0.85) were inversely related to childhood asthma in the logistic regression models. Pneumonia infection (OR = 2.24; 95% CI: 1.21, 4.16) and mold or dampness in the home (OR = 1.87; 95% CI: 1.18, 2.97) in the first year of life were positively associated with asthma. Conclusion. Our results suggest that the hygiene hypothesis is also applicable in the Chilean setting, a South American country in epidemiological transition.

• asthma
• case–control study
• Chile
• first year of life
• infancy
• hygiene hypothesis

Acknowledgments

The authors are very grateful for the efforts of all field workers and technical staff (Gisela Dietrich-Gümperlein, Silvia Grau, Beate Messing, Pamela Avila, Pedro Zamorano Aguilar, Kathrin Suttner, Johanna Wagner, and Alexei Cuevas Zhbankova) for their dedication to the study. The authors thank Betty Bisdorff for reading the manuscript. Parts of this study were used for a MD and a PhD thesis. The authors are grateful to the participants for their contribution.

The research was made possible by funding by the German Research Collaboration with Developing Countries Program (DFG/BMZ), the DAAD (German Academic Exchange Service), and the German Federal Ministry of Education and Research (BMBF, International Office).

Declaration of Interest

The authors report no competing interests. The authors alone are responsible for the content and writing of this paper.