Effect of sex on the association between arterial partial pressure of oxygen and in-hospital mortality in ICU patients with cardiogenic shock: a retrospective cohort study

BACKGROUND: Maintaining tissue perfusion and oxygen supply are essential for cardiogenic shock (CS) treatment. Sex has been reported to be associated with mortality and oxygen use in patients with CS. Males and females respond differently to hypoxia. We designed this cohort study to evaluate the effects of sex on the association between the arterial partial pressure of oxygen (PaO(2)) and in-hospital mortality. METHODS: We used the Medical Information Mart for Intensive Care (MIMIC) IV database for this cohort study. The outcome was in-hospital mortality. The relationship between the PaO(2) and in-hospital mortality was compared with sex (via an interaction test) using multivariable Cox regression models. Presence of interaction between PaO(2) and sex was tested by using inter interaction terms. RESULTS: A total of 1,772 patients with CS were enrolled in this study. The association between PaO(2) and in-hospital mortality appeared to differ between males and females [hazard ratio (HR): 0.997, 95% confidence interval (CI): 0.995–0.999 vs. HR: 1.002, 95% CI: 0.999–1.003, P for interaction =0.002]. We repeated the analyses, based on different PaO(2) category (PaO(2) <60 mmHg; PaO(2) 60–100 mmHg; PaO(2) >100 mmHg) and the results remained stable, P for interaction =0.008. CONCLUSIONS: Sex affects the relationship between PaO(2) and in-hospital mortality in CS patients. Our findings may lead to the development of individualized therapies that focus on the use of different target oxygen partial pressures in different sexes to treat patients with CS.