Yongli Liu, Wei Zhao, Chenyang Hu, Yuxin Zhang, Yiqing Qu

Department of Pulmonary and Critical Care Medicine, Qilu Hospital of Shandong University, Shandong Key Laboratory of Infectious Respiratory Diseases, Jinan, People’s Republic of China

Correspondence: Yiqing Qu, Department of Pulmonary and Critical Care Medicine, Qilu Hospital of Shandong University, Wenhuaxi Road 107#, Jinan, 250012, People’s Republic of China, Tel +8653182169335, Fax +8653182967544, Email quyiqing@sdu.edu.cn

Background: Among critically ill patients, chronic obstructive pulmonary disease (COPD) is an independent risk factor for death. Recently, biomarkers such as neutrophil-lymphocyte ratio (NLR) and albumin (ALB) have been used to predict the prognosis in patients with COPD. However, the association between NLR/ALB and all-cause mortality in critically ill COPD patients remains unclear. This study aims to explore the association between the NLR/ALB and prognosis in critically ill patients with COPD.
Methods: Data was sourced from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Primary outcome was 28-day all-cause mortality, with secondary outcomes being in-hospital and 90-day all-cause mortality. The area under the receiver operating characteristic curve (AUROC) was calculated to compare prognostic accuracy of NLR, NLR/ALB, PLR, SII and MLR variables. After identifying the most predictive factor, KM survival curves, Cox models and subgroup analyses were used to examine NLR/ALB’s relationship with mortality in critically ill COPD patients. Additionally, patients with COPD from the National Health and Nutrition Examination Survey data (1999– 2018) was used with Cox regression to investigate NLR/ALB’s correlation with all-cause mortality in COPD patients.
Results: 1916 critically ill COPD patients from MIMIC IV, divided into quartiles by NLR/ALB levels: Q1 (NLR/ALB< 1.108), Q2 (2.095>NLR/ALB≥ 1.108), Q3 (4.221>NLR/ALB≥ 2.095), Q4 (NLR/ALB≥ 4.221). In multivariate Cox regression, Q4 vs Q1: 28-day mortality HR=2.27 (95% CI: 1.63– 3.16); 90-day mortality HR=2.06 (95% CI: 1.56– 2.71); in-hospital mortality HR=1.93 (95% CI: 1.35– 2.77); P< 0.001. Subgroup analyses showed that the correlation between NLR/ALB and 28-day mortality was stable Additionally, we recruited 2,003 COPD patients from the NHANES that found NLR/ALB also correlated with all-cause mortality in COPD (In multivariate Cox regression: Q4 vs Q1 hR=1.92 (95% CI: 1.45– 2.55, P< 0.001)).
Conclusion: Elevated NLR/ALB levels are associated with increased all-cause mortality in critically ill patients with COPD.

Keywords: critically ill patients with COPD, COPD, NLR/ALB, mortality