Table 3.

Cox regression analyses to evaluate the probability for high-flow nasal cannula or mechanical ventilation according to time point of dexamethasone administration

Variable	Univariable analysis		p-value	Multivariable analysis (model 1)		p-value	Multivariable analysis (model 2)		p-value
	HR	95% CI		HR	95% CI		HR	95% CI
Age	1.020	0.996–1.045	0.101	-	-	-	-	-	-
Female sex	0.655	0.319–1.344	0.249	1.142	0.499–2.613	0.753	0.945	0.417–2.144	0.893
Current smoker	2.448	1.009–5.944	0.048	2.071	0.726–5.903	0.173	1.310	0.421–4.073	0.641
Charlson comorbidity index	1.147	0.977–1.347	0.095	1.032	0.850–1.253	0.750	0.976	0.805–1.183	0.803
SOFA score	1.245	1.101–1.409	<0.001	1.182	0.992–1.408	0.062	1.157	0.955–1.402	0.135
SAPS II	1.089	1.049–1.131	<0.001	-	-	-	-	-	-
No. of lymphocytes at development of hypoxemia	0.999	0.998–1.000	0.036	0.999	0.998–1.000	0.023	0.999	0.998–1.000	0.034
Remdesivir	2.358	1.184–4.695	0.015	1.733	0.847–3.546	0.133	1.544	0.721–3.308	0.264
Early dexamethasone	0.344	0.169–0.698	0.003	0.440	0.211–0.915	0.028	-	-	-
Initiation time of dexamethasone treatment	1.139	0.902–1.439	0.275	-	-	-	1.180	0.880–1.582	0.268

Values are presented as the odds ratio and 95% confidence interval.

In model 1, early dexamethasone (initiation time of dexamethasone treatment within 24 hours) was used as a categorical variable for multivariable analysis. In model 2, initiation time of dexamethasone treatment was used as a continuous variable for multivariable analysis. multivariable dox regression analysis was adjusted by covariates including SOFA score and SAPS II.

Age and SAPS II are not included in multivariable analysis due to multicollinearity (variance inflation factor >4).

HR: hazard ratio; CI: confidence interval; SOFA: Sequential Organ Failure Assessment; SAPS: Simplified Acute Physiology Score.