This observational study was submitted for approval to the Ethics Committee of the Organization (Fondazione IRCCS Cà Granda - Ospedale Maggiore Policlinico, Milan, Italy) on October 24, 2012. The transferral of patient records (concerning the 2007-2013 visits) from the electronic database of the centre to the study database has been started on June 2013 and will terminate on September 2014.