Table 4 Comparative data between the group with pneumonia and those without pneumonia

Sex, (female), n(%)

328 (49.2%)

248 (51.6%)

80 (43.2%)

0.055

Age (IQR)

67.0 (53.0–77.0)

68.0 (55.0–78.0)

64.0 (49.5–75.0)

0.024

Smoking, n(%)

198 (29.7%)

134 (27.9%)

64 (34.6%)

0.088

COPD*, n(%)

160 (24.0%)

115 (23.9%)

45 (24.3%)

0.910

Pregnancy, n(%)

5 (0.8%)

1 (0.2%)

4 (2.2%)

0.023

Obesity, n(%)

93 (14.0%)

60 (12.5%)

33 (17.8%)

0.074

Cardiac disease, n(%)

221 (33.3%)

163 (34.1%)

58 (31.4%)

0.522

Chronic kidney disease, n(%)

84 (12.6%)

58 (12.1%)

26 (14.1%)

0.487

Diabetes, n(%)

193 (29.0%)

136 (28.3%)

57 (30.8%)

0.518

Immunosuppression, n(%)

136 (20.4%)

108 (22.5%)

28 (15.1%)

0.036

 HIV**, n(%)

45 (6.8%)

32 (6.7%)

13 (7.0%)

0.863

 Malignancy, n(%)

42 (6.3%)

32 (6.7%)

10 (5.4%)

0.553

 Corticotherapy, n(%)

18 (2.7%)

17 (3.5%)

1 (0.5%)

0.033

 Others, n(%)

31 (4.7%)

27 (5.6%)

4 (2.2%)

0.058

Vaccinated, n(%)

258 (38.7%)

195 (40.5%)

63 (34.1%)

0.124

Cough, n(%)

573 (86.0%)

415 (86.3%)

158 (85.4%)

0.771

Fever, n(%)

476 (71.5%)

330 (68.6%)

146 (78.9%)

0.008

Myalgia, n(%)

166 (24.9%)

109 (22.7%)

57 (30.8%)

0.029

Dyspnoea, n(%)

446 (67.0%)

309 (64.2%)

137 (74.1%)

0.016

State of confusion, n(%)

64 (9.6%)

37 (7.7%)

27 (14.6%)

0.007

Season 12–13

51 (7.7%)

35 (7.3%)

16 (8.6%)

0.472

Season 13–14

116 (17.4%)

78 (16.2%)

38 (20.5%)

Season 14–15

248 (37.2%)

185 (38.5%)

63 (34.1%)

Season 15–16

251 (37.7%)

183 (38.0%)

68 (36.8%)

Subtype, n(%). H1N1

242 (36.3%)

161 (33.5%)

81 (43.8%)

0.066

H3N2

241 (36.2%)

186 (38.7%)

55 (29.7%)

Influenza A no subtype

33 (5.0%)

23 (4.8%)

10 (5.4%)

Influenza B

150 (22.5%)

111 (23.1%)

39 (21.1%)

Heart rate, median (IQR), n total

96.0 (82.0–109.0)

95.0 (82.0–108.0)

98.5 (82.3–112.8)

0.062

Systolic blood pressure [mmHg], median (IQR), n total

131.0 (113.0–147.0)

131.0 (114.3–146.0)

130.0 (110.0–149.0)

0.557

Respiratory frequency, median (IQR), n

26.0 (20.0–32.0)

26.0 (20.0–32.0)

25.0 (20.0–32.0)

0.880

Oxygen saturation [%], median (IQR), n

93.0 (90.0–96.0)

94.0 (91.0–96.0)

92.0 (88.0–95.0)

< 0.001

Oxygen saturation < 93%, n(%)

262 (40%)

170 (35,8%)

92 (51,1%)

< 0.001

Horowitz Index (PaO₂/FiO₂⁾, median (IQR), n

276.2 (242.9–309.5)

281.0 (250.0–314.3)

266.7 (223.8–304.8)

< 0.001

Alveolar-arterial gradient, median (IQR), n

46.0 (38.0–55.5)

45.0 (36.9–53.8)

49.2 (41.0–59.0)

< 0.001

Alveolar-arterial gradient adjusted for age, median (IQR), n

17.4 (14.3–19.7)

17.4 (14.7–19.7)

17.2 (13-19.9)

0.003

Lymphocyte [x10⁹/L] median (IQR), n

1000.0 (670.0–1447.5)

1000.0 (670.0–1407.5)

980.0 (662.5–1520.0)

0.732

Hematocrit [%], median (IQR), n

39.1 (34.7–42.7)

39.2 (34.8–43.0)

38.8 (34.1–42.4)

0.355

Platelet [x109/L], median (IQR)

201,500 (151,000–258,250)

201,000(148,000–253,000)

202,000 (159,500–276,500)

0.196

Creatinine [mg/dl], median (IQR), n

0.9 (0.7–1.1)

0.9 (0.7–1.1)

0.9 (0.7–1.3)

0.251

Urea [mg/d], median (IQR), n

36 (28–53)

36 (28–52)

38 (29–65.5)

0.096

Albumin [mg/dl], median (IQR), n

34.6 (31- 37.3)

35 (31.9–37.9)

32.5 (29.2–36.4)

< 0.001

C-reactive protein [mg/dl], median (IQR), n

5.1 (2.0–11.9)

4 (1.6–9)

11.3 (4.7–22)

< 0.001

Pleural effusion, n (%)

28 (4.2%)

16 (3.3%)

12 (6.5%)

0.069

Septic shock, n(%)

50 (7.5%)

16 (3.3%)

34 (18.4%)

< 0.001

Mechanical ventilation, n(%)

67 (10.1%)

22 (4.6%)

45 (24.3%)

< 0.001

Intensive care unit admission, n(%)

73 (11.0%)

28 (5.8%)

45 (24.3%)

< 0.001

Death, n(%)

39 (5.9%)

17 (3.5%)

22 (11.9%)

< 0.001

Bacterial coinfection, n(%)

60 (9.0%)

34 (7.1%)

26 (14.1%)

0.005

Nosocomial infection, n(%)

76 (11.4%)

66 (13.7%)

10 (5.4%)

0.003