CAT and chronic obstructive pulmonary disease: Values of MMRC, CAT, SGRQ score, 6-min walk distance and BODE index at visit 1 and 2 were significantly associated with optimism scores at visit 3 in multivariable analysis, and changes of MMRC, CAT, SGRQ score, and BODE index 5 and 10 years previously were also significantly associated with visit 3 optimism in smokers with and without COPD (Additional file 1: Table S5).