. 2021 Jul 1;12:620187. doi: 10.3389/fphar.2021.620187

TABLE 2.

Association between baseline variables and time to death.

Group variables	Variable	HR^c	95%CI	p-value	HR^d	95%CI	p-value	HR^e	95%CI	p-value
Demographic variables	Male	1.68	0.70–4.08	0.248
Demographic variables	Age (years) ^a	1.04	1.01–1.07	0.015				1.05	1.02–1.09	0.001
COVID-19 wave	Second	1.26	0.64–2.50	0.503
Smoking habit	Smokers	2.24	0.60–8.34	0.231
Smoking habit	Ex-smokers	1.04	0.41–2.63	0.930
Comorbidities and physical examination	Hypertension	1.60	0.79–3.24	0.196
	Dyslipidemia	1.70	0.86–3.38	0.128
	Cardiovascular disease	1.51	0.77–2.98	0.230
	Diabetes mellitus	2.26	1.09–4.68	0.029	2.25	1.08–4.69	0.030	2.63	1.23–5.64	0.013
	Previous pulmonar disease	1.44	0.68–3.03	0.340
	Immunosuppression	4.85	2.15–10.95	<0.001	4.87	2.15–11.07	<0.001	3.15	1.17–8.51	0.024
	Confirmed diagnosis by PCR	0.59	0.26–1.33	0.204
Pharmacological treatment	Lopinavir/ritonavir	0.75	0.38–1.48	0.407
	Azytromicine	0.85	0.43–1.69	0.640
	Anakinra	0.99	0.35–2.83	0.993
	Methylprednisolone	0.93	0.33–2.66	0.899
	Ciclosporine	2.59	0.35–19.36	0.354
	Pulses of methylprednisolone	0.85	0.42–1.72	0.644
	Colchicine	1.27	0.17–9.35	0.814
	Hydroxycloroquine	0.79	0.40–1.57	0.507
	More than one dose of TCZ	1.03	0.46–2.29	0.941
	Days since symptoms until TCZ^a	0.93	0.86–1.02	0.117
	Days since diagnosis until TCZ ^a	1.06	1.03–1.09	<0.001	1.07	1.03–1.10	<0.001	1.05	1.00–1.09	0.032
Symptoms and signs pre-TCZ	Dry cough	1.00	0.47–2.16	0.991
	Fatigue	0.75	0.38–1.48	0.411
	Myalgia	0.35	0.15–0.86	0.021	0.35	0.15–0.86	0.021
	Dyspnea	0.69	0.35–1.38	0.294
	Headache	0.70	0.25–2.00	0.511
	Diarrhea	0.68	0.16–2.87	0.602
	Acute Respiratory distress syndrome	0.68	0.30–1.53	0.353
	Acute cardiac injury	3.22	0.76–13.64	0.113
	Thrombosis	0.88	0.12–6.43	0.897
	Acute renal injury	1.95	0.75–5.08	0.172
	Scale ERVI^a	1.02	0.83–1.25	0.858
	Hospitalization when TCZ administration	0.64	0.30–1.35	0.243
	Fever	0.62	0.25–1.53	0.301
Laboratory findings pre-TCZ	Total serum proteins (gr/dL) ^b	0.53	0.31–0.92	0.025
	Aspartate transaminase (U/L)^b	0.78	0.39–1.56	0.481
	Alanine transaminase (U/L)^b	0.55	0.30–1.00	0.052
	γ-Glutamyl transferase (U/L)^b	0.67	0.38–1.18	0.161
	Procalcitonin (ng/ml)^b	0.97	0.74–1.26	0.804
	Albumin (gr/dL)^b	0.40	0.05–3.50	0.409
	Interleukin-6 (pg/ml)^b	1.08	0.79–1.48	0.611
	Lactate deshydrogenase (U/L)^b	1.87	0.55–6.29	0.312
	C-reactive protein (mg/L)^b	0.93	0.66–1.31	0.669
	Ferritin (ng/ml)^b	1.24	0.82–1.88	0.302
	Leukocyte count (/μL)^b	0.69	0.31–1.54	0.368
	Neutrophil count (/μL)^b	0.69	0.32–1.48	0.343
	Lymphocyte count (/μL)^b	0.88	0.47–1.65	0.695
	Platelet count (/μL) ^b	0.20	0.10–0.40	<0.001	0.20	0.10–0.41	<0.001	0.27	0.11–0.69	0.006
	Fibrinogen (mg/dl)^b	1.00	1.00–1.00	0.440
	Troponin I (pg/ml) ^b	1.35	1.08–1.69	0.007
	D-dimer (mg/L)^b	1.15	0.86–1.52	0.342
	PaO₂/FiO₂ (mmHg)^b	0.79	0.30–2.25	0.663
	Temperature°C ^a	0.39	0.21–0.76	0.005

PCR: polymerase Chain Reaction; Scale ERVI: X-ray scale for assessment of hospital admission; TCZ: Tocilizumab; HR: hazard ratio; CI: confidence interval. For dichotomous variables, the reference category was “no” except hospitalization when TCZ administration that it was “general ward” (comparison ICU) and confirmed diagnosis-PCR that it was “suspicious diagnosis with negative PCR” (comparison confirmed positive PCR result). For smoking habit the reference was “never smoker”. Highlighted in bold if p < 0.05.

^aHazard ratios are expressed per unit increase in the variable.

^bLog-transformed quantitative variables.

^cObtained with Cox’s univariate proportional hazard regression models.

^dObtained with stepwise regression model within groups of variables, including variables with p-value <0.2 in univariate analysis, except total serum proteins (N = 99), troponin I (N = 80) and temperature (N = 60) which were excluded from multivariate models because of presenting >10% of missing values.

^eObtained with stepwise regression including variables retained in models by group.