Funding for this research was provided by:
Fundo Europeu de Desenvolvimento Regional (FCOMP-01-0124-FEDER-021181)
Fundação para a Ciência e a Tecnologia (PTDC/SAU-EPI/122460/2010, SFRH/BPD/75918/2011)
Epidemiology Research Unit – Institute of Public Health, University of Porto (UID/DTP/047507/2013)