Fig. 1

Estimated survival probability of multivariable Cox regression model with time-dependent corticosteroid treatment. Cox regression model with corticosteroid treatment was time-varying variable, adjusting for age, sex, SOFA score at hospital admission, propensity score of corticosteroid treatment, comorbidities (diabetes, hypertension, chronic pulmonary disease, chronic renal or liver disease, solid malignant tumor, hematologic malignancy, and immunosuppressive status), antiviral treatment (Lopinavir–Ritonavir, oseltamivir, and ganciclovir), and respiratory supports (high-flow oscillation oxygen, noninvasive mechanical ventilation, and invasive mechanical ventilation). Propensity score was calculated by a non-parsimonious logistic regression model that included: age, sex, SOFA score, temperature, respiratory rate, SpO₂/FiO₂ ratio, blood lymphocyte count, blood neutrophil count, and level of c-reactive protein at hospital admission. ARDS, acute respiratory distress syndrome; SOFA, sequential organ failure assessment