Open Access Research article

Socioeconomic trajectory from birth to adolescence and lung function: prospective birth cohort study

Ana MB Menezes1*, Samuel C Dumith2, Rogélio Perez-Padilla3, Ricardo B Noal1, Fernando C Wehrmeister1, Jeovany Martínez-Mesa1, Cora LP Araújo1 and Pedro C Hallal2

Author Affiliations

1 Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil

2 Postgraduate Program in Epidemiology, and Physical Activity Epidemiology Research Group, Federal University of Pelotas, Pelotas, Brazil

3 National Institute of Respiratory Diseases, Mexico City, Mexico

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BMC Public Health 2011, 11:596  doi:10.1186/1471-2458-11-596

Published: 27 July 2011

Abstract

Background

Socioeconomic status (SES) has been shown to be an important contributor to lung function. The aim of this study was to evaluate the association between lung function in adolescence and (a) SES at birth; (b) SES in adolescence; (c) SES trajectory from birth to adolescence ('never poor', 'non poor-poor', 'poor-non poor' and 'always poor'). Additionally, we investigate the role of adolescent and parental variables at mediating these associations.

Methods

Prospective birth cohort study in Pelotas, Brazil, including 4,005 adolescents (mean age: 14.7 years) followed up from birth. Lung function was measured by spirometry. Outcome variables were forced expiratory volume in one second in liters (FEV1) and forced vital capacity also in liters (FVC).

Results

Mean FEV1 was 3.46 L (95%CI 3.43-3.49) among boys and 2.93 L (95%CI 2.91-2.95) among girls. Mean FVC was 4.00 L (95%CI 3.97; 4.04) among boys and 3.30 L (95%CI 3.27; 3.32) among girls. SES at birth, in adolescence and its trajectory from birth to adolescence were inversely associated with lung function in both adolescent boys and girls. After adjustment for mediating variables, coefficients were largely reduced, particularly among boys, and the main predictor of change in coefficients was the inclusion of height in the models.

Conclusion

Low income adolescents from Brazil present impaired lung function as compared to the better off, and this is largely explained by height.

Keywords:
Spirometry; socioeconomic factors; adolescent; cohort studies; developing countries