Exacerbation Burden in COPD and Occurrence of Mortality in a Cohort of Italian Patients: Results of the Gulp Study oleh Santus P, Di Marco F, Braido F, Contoli M, Corsico AG, Micheletto C, Pelaia G, Radovanovic D, Rogliani P, Saderi L, Scichilone N, Tanzi S, Vella M, Boarino S, Sotgiu G, Solidoro P