About the Authors

Luís Alves

lalves@med.up.pt

Affiliations Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, Portugal, Institute of Public Health - University of Porto (ISPUP), Porto, Portugal, Santo André de Canidelo Health Family Unit, Vila Nova de Gaia, Portugal

Ana Azevedo

Affiliations Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, Portugal, Institute of Public Health - University of Porto (ISPUP), Porto, Portugal

Susana Silva

Affiliations Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, Portugal, Institute of Public Health - University of Porto (ISPUP), Porto, Portugal

Henrique Barros

Affiliations Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, Portugal, Institute of Public Health - University of Porto (ISPUP), Porto, Portugal

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: AA HB. Performed the experiments: LA AA. Analyzed the data: LA AA. Contributed reagents/materials/analysis tools: AA HB. Wrote the paper: LA AA SS. Classified occupations: LA SS. Interpreted the data and revised the manuscript for important intellectual content: LA AA SS HB.