Nonlinear association between admission oxygen partial pressure and in-hospital and one-year all-cause mortality in patients with coronavirus disease pneumonia: A retrospective cohort study.

BACKGROUND

This study investigated the correlation between admission partial pressure of arterial oxygen (PaO) levels and both in-hospital mortality and 1-year all-cause mortality among patients diagnosed with coronavirus disease (COVID-19) pneumonia.

METHODS

This retrospective cohort study included patients with COVID-19 pneumonia admitted to the First Hospital of Jinzhou Medical University. Restricted cubic spline regression and logistic regression analyses were employed to assess the relation between PaO levels and the risk of in-hospital mortality and all-cause mortality within 1 year. Subgroup analyses were performed, stratified by age, sex, presence of cardiac disease, diabetes, hypertension, whether supplemental oxygen was provided during arterial blood gas analysis, and severity of pneumonia.

RESULTS

The study included 737 participants with in-hospital and 1-year all-cause mortality rates of 15.7% and 26.7%, respectively. Restricted cubic spline analysis revealed an L-shaped association between admission PaO levels and in-hospital mortality ( nonlinear <0.001) and a U-shaped relation with 1-year all-cause mortality ( nonlinear <0.001), with a nadir risk of 82 mmHg. Threshold analyses indicated an odds ratio of 0.931 (95% confidence interval (CI): 0.91-0.952) for in-hospital mortality and 0.951 (95% CI: 0.933-0.969) for 1-year all-cause mortality when PaO was <82 mmHg. Conversely, when PaO was ≥82 mmHg, the odds ratio for in-hospital mortality was 1.022 (95% CI: 0.991-1.055), and for 1-year all-cause mortality was 1.029 (95% CI: 1.004-1.054).

CONCLUSIONS

This study revealed a nonlinear relation between PaO levels at admission and both in-hospital mortality and 1-year all-cause mortality in patients with COVID-19 pneumonia, with a notable inflection point observed at approximately 82 mmHg.