Association Between Serum Anion Gap and Mortality in Critically Ill Patients with COPD in ICU: Data from the MIMIC IV Database

Xiaojing Chen,1– 3,* Qilin Yang,4,* Li Gao,1– 3 Weinan Chen,1 Xiaoyu Gao,1– 3 Yameng Li,1– 3 Liying Ao,5 Dejun Sun1– 3 1Department of Respiratory and Critical Care Medicine, Inner Mongolia People’s Hospital, Hohhot, 010017, People’s Republic of China; 2NHC Key Laboratory of Diagnosis & Treatment of COPD, Inner Mongolia People’s Hospital, Hohhot, 010017, People’s Republic of China; 3Inner Mongolia Key Laboratory of Respiratory Diseases, Inner Mongolia People’s Hospital, Hohhot, 010017, People’s Republic of China; 4Department of Critical Care, the Second Affiliated Hospital of Guangzhou Medical University, Guangzhou, People’s Republic of China; 5Department of Otolaryngology, Inner Mongolia People’s Hospital, Hohhot, 010017, People’s Republic of China*These authors contributed equally to this workCorrespondence: Dejun Sun, Department of Respiratory and Critical Care Medicine, Inner Mongolia People’s Hospital, No. 26 Zhaowuda Road, Saihan District, Hohhot, 010017, People’s Republic of China, Email nmg_sdj@163.comBackground: Serum anion gap (AG) has been proven to be associated with prognosis in critically ill patients. However, few studies have investigated the association between AG and all-cause mortality in critically ill patients with chronic obstructive pulmonary disease (COPD).Objective: We hypothesized that the initial AG level would predict the mortality risk in critically ill patients with COPD.Methods: This retrospective cohort study was based on the Medical Information Mart for Intensive Care (MIMIC) IV database. We extracted demographics, vital signs, laboratory tests, comorbidity, and scoring systems from the first 24 hours after patient ICU admission. Multivariable logistic regression analysis models were used to explore the association between serum AG levels and mortality. Interaction and stratified analyses were conducted including age, gender and comorbidity.Results: A total of 5531 critically