Table 1 Baseline characteristics and 30-day endpoints for the analyzed study population stratified by respiratory infections

Sociodemographics

 Age [years] median (IQR)

73.0 (59.0, 82.0)

73.0 (60.0, 81.0)

64.5 (57.0, 74.0)

 < 0.01

 Male gender, n (%)

361 (41.2%)

168 (45.3%)

47 (63.5%)

 < 0.01

Pre-existing risk-factors and medication

 Smoker

219 (25.7%)

123 (34.1%)

4 (7.0%)

 < 0.01

 Steroid intake

69 (8.1%)

69 (18.9%)

1 (1.4%)

 < 0.01

 Immunosuppressive therapy

14 (1.6%)

3 (0.8%)

3 (4.1%)

0.11

Comorbidities

 Cancer, n (%)

110 (12.6%)

42 (11.3%)

6 (8.1%)

0.48

 Coronary artery disease, n (%)

176 (20.1%)

85 (22.9%)

18 (24.3%)

0.42

 Chronic heart failure, n (%)

151 (17.2%)

55 (14.8%)

2 (2.7%)

 < 0.01

 Solid organ transplant recipient, n (%)

2 (0.2%)

1 (0.3%)

0 (0.0%)

0.91

 Chronic kidney disease, n (%)

196 (22.4%)

79 (21.3%)

18 (24.3%)

0.82

 Liver cirrhosis, n (%)

19 (2.2%)

4 (1.1%)

0 (0.0%)

0.20

 Obesity (BMI > 30 kg/m2), n (%)

35 (17.7%)

32 (18.4%)

23 (31.1%)

0.04

Initial vital signs

 Blood pressure, systolic [mmHg], median (IQR)

132.0 (119.0, 148.0)

138.0 (120.0, 150.0)

141.5 (126.0, 156.0)

 < 0.01

 Blood pressure, diastolic [mmHg], median (IQR)

74.0 (65.0, 82.0)

78.0 (66.2, 85.0)

81.5 (72.0, 88.0)

 < 0.01

 Heart rate [bpm], median (IQR)

95.0 (82.0, 107.0)

90.0 (80.0, 101.0)

87.5 (77.5, 97.5)

 < 0.01

 Respiratory rate [breaths/min], median (IQR)

20.0 (16.0, 25.0)

20.0 (16.0, 26.0)

22.0 (18.0, 27.0)

0.39

 Temperature [°C], median (IQR)

38.1 (37.2, 38.9)

37.3 (36.7, 38.1)

37.7 (37.2, 38.3)

 < 0.01

 Temperature > 38 °C, n (%)

446 (50.9%)

105 (28.3%)

37 (50.0%)

 < 0.01

 SpO₂ [%], median (IQR)

93.0 (89.0, 96.0)

93.0 (89.0, 96.0)

93.0 (87.8, 95.3)

0.99

Initial laboratory findings

 Blood gas analysis for ambient air, n (%)

n = 455

n = 198

n = 54

  FiO₂ [%], median (IQR)

21

21

21

N/A

  PO₂ [mmHg], median (IQR)

62 (57, 76)

66 (58, 76)

68 (61, 72)

0.9

  PCO₂ [mmHg], median (IQR)

35 (31, 38)

36 (32, 41)

31 (29, 33)

 < 0.01

  Lactate [mmol/l], median (IQR)

1.6 (1.0, 2.3)

1.4 (1.1, 1.6)

1.3 (0.9, 1.7)

0.1

Blood gas analysis for initial O₂, n (%)

n = 421

n = 173

n = 20

 FiO2 [%], median (IQR)

32 (28, 36)

28 (28, 36)

47 (32, 95)

 < 0.01

 PO₂ [mmHg], median (IQR)

60 (53,70)

62 (53, 74)

65 (56, 75)

0.24

 PCO₂ [mmHg], median (IQR)

35 (31, 39)

38 (34, 47)

32 (31, 35)

 < 0.01

 Lactate [mmol/l], median (IQR)

1.3 (1.0, 1.8)

1.0 (0.9, 1.4)

1.2 (1.0, 1.5)

0.11

Leukocytes [G/L], median (IQR)

12.0 (9.0, 16.4)

9.7 (7.5, 13.3)

7.3 (4.6, 8.7)

 < 0.01

Sodium [mmol/L], median (IQR)

136.0 (133.0, 138.0)

136.0 (134.0, 139.0)

136.0 (133.0, 139.0)

 < 0.01

Glucose [mmol/L], median (IQR)

7.1 (6.0, 8.5)

6.7 (5.8, 7.9)

6.7 (5.9, 8.6)

0.01

Urea [mmol/L], median (IQR)

7.1 (4.9, 10.5)

6.5 (4.4, 9.6)

5.9 (4.4, 9.4)

0.06

CRP [mg/L], median (IQR)

154.5 (74.2, 251.9)

41.0 (14.0, 98.4)

94.3 (49.9, 150.0)

 < 0.01

PCT [µg/L], median (IQR)

0.46 (0.15, 2.66)

0.12 (0.08, 0.20)

0.11 (0.05, 0.26)

 < 0.01

Creatinine [µmol/L], median (IQR)

89.0 (69.0, 113.0)

84.0 (66.0, 106.0)

91.0 (77.0, 115.0)

0.02

Pro-Endothelin-1 [pmol/L], median (IQR)

113 (81.0, 169.0)

96.0 (67.0, 139.0)

57.0 (41.4, 81.8)

 < 0.01

Outcomes within 30 days

 ICU care, n (%)

80 (9.1%)

13 (3.5%)

22 (29.7%)

 < 0.01

 30-day mortality, n (%)

49 (5.6%)

10 (2.7%)

17 (23.0%)

 < 0.01

 Length of stay [day], median (IQR)

8.0 (5.0, 13.0)

7.0 (3.0, 11.0)

9.0 (5.0, 14.0)

 < 0.01