Table 4– Univariate model (Chi-squared test) for 30-day mortality, including potential risk factors influencing outcome related to underlying conditions, severity of the clinical presentation, and microbiological and therapy-related factors

	OR (95% CI)	p-value
Underlying and demographic conditions
Male sex	4.81 (1.80–12.55)	<0.01
Age	1.02 (0.99–1.04)	0.08
Alcoholism	3.79 (1.67–8.56)	<0.01
Tobacco consumption	2.03 (0.94–4.45)	0.07
Charlson score	1.25 (1.09–1.44)	<0.01
Immunocompromise	2.51 (1.04–6.08)	0.05
Severity at admission
P_a,O₂/F_I,O₂ <250	6.20 (2.75–13.93)	<0.001
Multilobar involvement	5.59 (2.38–13.59)	<0.001
Need for vasopressors	4.15 (1.90–9-07)	<0.001
Need for mechanical ventilation	3.53 (1.70–7.79)	0.01
Severity of illness scores
PSI class V	14.91 (5.08–43.9)	<0.001
ATS/IDSA criteria	6.65 (2.88–15.36)	<0.001
Antibiotic resistance
Penicillin
Macrolide	4.43 (2.02–9.72)	<0.01
Microbiology
H serotypes	1
O serotypes	2.36 (0.63–9.05)	0.2
L serotypes	10.34 (2.94–36.5)	<0.001
Antibiotic therapy
Monotherapy	1.94 (0.90–4.16)	0.1
Combination therapy	1

H serotypes (reference category): 1, 5 and 7F. L serotypes: 3, 6A, 6B, 8, 19F and 23F. O serotypes: non-L, non-H serotypes. P_a,O₂: arterial oxygen tension; F_I,O₂: inspiratory oxygen fraction; PSI: Pneumonia Severity Index; ATS: American Thoracic Society; IDSA: Infectious Diseases Society of America.