Table 2.

Relative risks for outcomes in early antibiotic use (EAU) or non-early antibiotic use (NEAU) groups under the mixed-effect model before and after propensity score matching.

	Unmatched (n=1373)								Matched (n=746)a
	Crudeb				Mixed-effect modelc				Crudeb				Mixed-effect modelc
	HR	95% CI		P-value	HR	95% CI		P-value	HR	95% CI		P-value	HR	95% CI		P-value
Progression to severe disease	1.560	1.232	1.974	0.0002	1.555	1.227	1.970	0.0003	1.416	1.069	1.876	0.0154	1.416	1.069	1.876	0.0154
	OR	95% CI		P-value	OR	95%CI		P-value	OR	95% CI		P-value	OR	95% CI		P-value
Length of stay>15 days	1.711	1.308	2.240	<0.0001	1.827	1.389	2.403	<0.0001	1.684	1.218	2.328	0.0016	1.784	1.279	2.487	0.0007
All-cause mortality (30 days)	3.070	1.008	9.348	0.0484	3.051	1.001	9.301	0.0498	1.182	0.237	5.909	0.8385	1.190	0.237	5.969	0.8324

OR, odds ratio; CI, confidence interval; HR, hazard ratio; COPD, chronic obstructive pulmonary disease; NSAIDs, non-steroidal anti-inflammatory drugs.

^aPropensity score matching was conducted to adjust for basic demographic characteristics (age and gender), symptoms (cough and fever), vital signs (diastolic blood pressure and respiratory rate), comorbidities (hypertension, diabetes, malignancy and COPD), treatments (antiviral drugs, NSAIDs, steroids, immunomodulators and biologics) and laboratory data on admission (white blood cell count, lymphocyte percentage and C-reactive protein).

^bCrude estimations were adjusted for basic demographic characteristics (age and gender), symptoms (cough and fever), comorbidities (hypertension, diabetes, and coronary heart disease, malignancy and COPD) and treatments (antiviral drugs, NSAIDs, steroids, immunomodulators and biologics).

^cSite (hospital) was modelled as a random effect in the multi-variate analyses.