1. Cardiology Department, Health Research Institute of the Balearic Islands (IdISBa), Hospital Universitari Son Espases , Palma , Spain
2. Centro Nacional de Investigaciones Cardiovasculares (CNIC) , Madrid , Spain
3. Facultad de Medicina, Universitat de les Illes Balears , Palma , Spain
4. Medical Statistics Department, London School of Hygiene and Tropical Medicine , London , UK