1. Osakidetza Basque Health Service, Donostialdea Integrated Health Organisation, Donostia University Hospital, Medical Library, San Sebastián, Spain
2. CIBERESP (CIBER of Epidemiology and Public Health), Madrid, Spain
3. Osakidetza Basque Health Service, Donostialdea Integrated Health Organisation, Donostia University Hospital, Clinical Epidemiology Unit, San Sebastián, Spain
4. Biodonostia Health Research Institute, San Sebastián, Spain