1. Epidemiology and Medical Statistics Unit, Department of Biomedical Sciences, University of Sassari–Research, Medical Education and Professional Development Unit, AOU Sassari, Sassari, Italy
2. Hygiene and Preventive Medicine, Department of Biomedical Sciences, University of Sassari, Sassari, Italy
3. World Health Organization Collaborating Centre for Tuberculosis and Lung Diseases, Fondazione S Maugeri, Care and Research Institute, Tradate, Italy