1 Clinical Epidemiology and Medical Statistics Unit, Department of Biomedical Sciences, University of Sassari, Research, Medical Education and Professional Development Unit, AOU Sassari, Italy.
2 WHO Collaborating Centre for TB and Lung Diseases, Fondazione S Maugeri, Care and Research Institute, Tradate 21049, Italy. Electronic address: giovannibattista.migliori@fsm.it.