1. Thoracic Surgery Unit, Università della Campania “Luigi Vanvitelli”, Naples, Italy
2. Thoracic Surgery Unit, Università La Sapienza, Policlinico Hospital, Rome, Italy
3. Thoracic Surgery Unit, Università La Sapienza, Sant’Andrea Hospital, Rome, Italy
4. Statistic Unit, Department of Public Health, University of Naples, ‘Federico II’, Naples, Italy