We evaluated the following variables in smokers with and without COPD at baseline and after 1 year : CAT score , age , sex , smoking status , pack-year history , BMI , modified Medical Research Council ( mMRC ) scale , 6-min walk distance ( 6MWD ) , lung function , BODE ( BMI , obstruction , dyspnea , exercise capacity ) index , hospital admissions , Hospital and Depression Scale , and the Charlson comorbidity index .