1 Faculty of Medicine, University of Porto, Portugal.
2 Faculty of Sciences, Department of Mathematic, University of Porto, Portugal.
3 Faculty of Sciences, Department of Mathematic, University of Porto, Portugal; Centre of Mathematics of the University of Porto, Portugal.
4 ARS Norte, Public Health Department, University of Porto, Portugal.
5 EPIUnit Institute of Public Health, University of Porto, Portugal; Chest Disease Center Vila Nova de Gaia, Portugal; Pulmonology, Centro Hospitalar de Vila Nova de Gaia/Espinho EPE, Portugal; Department of Clinical Epidemiology, Predictive Medicine and Public Health University of Porto Medical School, Porto, Portugal; raquel.duarte@chvng.min-saude.pt.