Hospitalization increases while economic status deteriorates in late stages of chronic obstructive pulmonary disease: the Korean National Health and Nutrition Examination Survey for 2007–2015

Hyung Koo Kang, Jae-Woo Jung, Min-Jong Kang, Deog Kyeom Kim, Hayoung Choi, Young Jae Cho, Seung Hun Jang, Chang Hoon Lee, Yeon Mok Oh, Jisook Park, Jae Yeol Kim