Ethical considerations

The use of two different recruitment methods was needed to respond to the different requirements of local Ethics Committees. According to the Ethics committees of Queens University and the Université de Montréal (Canadian sites), researchers are not allowed to directly contact potential participants to invite them to participate and invitations to participate in research projects need to be carried out by third parties (in this case, a primary care doctor). In the Universities of Caldas and Rio Grande do Norte and at the Albanian National Institute of Health, authorized researchers are allowed to invite participants directly by letter, phone or home visits.

The Research Ethics Committees at the Universidad de Caldas, Universidade Federal do Rio Grande do Norte, Albanian Institute of Public Health, Queens University and Centre de Recherche du Centre Hospitaliere de l’Université de Montréal approved the study, and written informed consent was obtained from all subjects prior to study participation.