Intensive care unit admission and associated factors in patients hospitalised for COVID-19: A national retrospective cohort study in Iran

OBJECTIVES: This study aimed to determine factors associated with intensive care unit (ICU) admission in patients hospitalised due to COVID-19. DESIGN: Retrospective cohort. SETTING: Confirmed hospitalised patients from all over Iran were considered for the study. PARTICIPANTS: All patients with COVID-19 admitted to the hospital from March 2020 to May 2021 were included by census. ICU admission was defined by the following criteria: (1) admission to the ICU ward; (2) level of consciousness (loss of consciousness); and (3) use of invasive ventilation. METHODS: This is a secondary data analysis from the Medical Care Monitoring Center. The association between different variables and ICU admission was assessed by forward Logistic regression and restricted cubic spline method. RESULTS: The mean age of the 1 469 620 patients with COVID-19 was 54.49±20.58 years old, and 51.32% of the patients were male. The prevalence of ICU admission was 19.19%. The mean age of patients admitted to the ICU was higher than that of other hospitalised patients (62.49±19.73 vs 52.59±20.31 years). The prevalence of ICU admission was 17.17% in the first, 21.52% in the second, 19.72% in the third, 21.43 in the fourth and 17.4% in the fifth wave. In the multivariable model, age groups, sex, waves of the epidemic, comorbidities and saturation of peripheral oxygen (SpO(2)) <93% and acute respiratory distress syndrome (ARDS) were associated with an increased odds of ICU admission. The OR for ICU admission indicates a significant protective effect at a young age and then a significant risk factor for admission to the ICU ward at an old age. CONCLUSIONS: Men, older adults, people who suffer from ARDS, patients with SpO(2) levels of less than 93% and cases with comorbidities had the highest odds of ICU admission. Therefore, these groups should take all necessary precautions to avoid contracting COVID-19.