Association between ROX index and in-hospital mortality in critically ill patients with chronic obstructive pulmonary disease: A retrospective cohort study based on two large databases. - Wang, Guangdong; Liu, Tingting; Ji, Wenwen; Li, TingTing; Wang, Zhuoyang; Hu, Tinghua; Wang, Xiaojian; Shi, Zhihong (Science Progress, 2026)