Table 1 Baseline and clinical characteristics of the study population

Age, years (mean ± SD)

70.8 ± 10.4

69.9 ± 10.5

75.3 ± 8.6

 < 0.001^a

Gender, n (%)

Male

248 (50.2)

210 (50.4)

38 (49.4)

0.871^b

Female

246 (49.8)

207 (49.6)

39 (50.6)

0.871^b

Laboratory test, median (IQR)

WBC count (10³/μL)

11.1 (8.0, 15.6)

10.9 (8.0, 15.1)

12.0 (9.1, 17.7)

0.084^c

Neutrophil count (10³/μL)

9.2 (6.2, 13.2)

8.8 (6.1, 13.0)

10.4 (7.2, 15.1)

0.019^c

Lymphocyte count (10³/μL)

0.9 (0.5, 1.6)

0.9 (0.5, 1.6)

0.8 (0.4, 1.2)

0.015^c

Platelet count (10³/μL)

236 (175, 308)

239 (175, 307)

224 (162, 309)

0.434^c

Hemoglobin (g/dL)

10.8 (9.6, 12.3)

10.9 (9.6, 12.4)

10.6 (9.5, 11.5)

0.145^c

Serum albumin (g/dL)

3.2 (2.7, 3.6)

3.3 (2.8, 3.7)

2.9 (2.6, 3.4)

 < 0.001^c

Serum sodium (mmol/L)

138 (134, 141)

137 (134, 141)

137 (134, 140)

0.592^c

Serum potassium (mmol/L)

4.2 (3.7, 4.7)

4.2 (3.7, 4.7)

4.1 (3.5, 4.6)

0.080^c

Serum calcium (mmol/L)

1.13 (1.07, 1.19)

1.13 (1.10, 1.19)

1.13 (1.10, 1.16)

0.982^c

pH

7.34 (7.25, 7.40)

7.34 (7.26, 7.40)

7.32 (7.25, 7.40)

0.503^c

pO₂ (mmHg)

103 (74, 187)

107 (76, 192)

88 (61, 167)

0.018^c

pCO₂ (mmHg)

67 (53, 72)

53 (44, 72)

52 (46, 71)

0.810^c

Bicarbonate (mmol/L)

28 (25, 33)

28 (25, 33)

30 (25,34)

0.574^c

ALT (IU/L)

23 (15, 40)

23 (15, 40)

21 (15, 40)

0.975^c

AST (IU/L)

27 (18, 42)

26 (18, 42)

27 (17, 46)

0.968^c

Serum creatinine (mg/dL)

1.0 (0.7, 1.4)

1.0 (0.7, 1.4)

1.0 (0.7, 1.3)

0.787^c

BUN (mmol/L)

25 (18, 38)

24 (18, 36)

28 (21, 44)

0.021^c

Mean vital signs, median (IQR)

Temperature (℃)

36.7 (36.4, 37.1)

36.7 (36.3, 37.1)

36.7 (36.4, 37.1)

0.738^c

MAP (mmHg)

77 (71, 85)

77 (71, 84)

75 (70, 83)

0.176^c

Heart rate (min⁻¹)

90 (80, 100)

89 (80, 99)

90 (81, 103)

0.142^c

Respiratory rate (min⁻¹)

20 (17, 23)

20 (17, 23)

20 (17, 23)

0.587^c

Comorbidities, n (%)

Hypertension

246 (49.8)

216 (51.8)

30 (39.0)

0.038^b

DM

137 (27.7)

124 (29.7)

13 (16.9)

0.021^b

CHD

112 (22.7)

94 (22.5)

18 (23.4)

0.352^b

CKD

83 (16.8)

75 (18.0)

8 (10.4)

0.101^b

Maligancy

131 (26.5)

108 (25.9)

23 (29.9)

0.468^b

Inflammatory indicators, median (IQR)

NLR

8.8 (5.0, 16.6)

8.8 (5.0, 16.6)

14.6 (6.6, 31.5)

 < 0.001^c

PLR

246.3 (133.9, 467.7)

237.5 (129.5, 436.9)

295.9 (175.6,593.2)

0.022^c

PNI

33.3 (28.6, 37.6)

33.8 (29.2, 38.0)

30.1 (26.2, 35.4)

 < 0.001^c

Scoring system, median (IQR)

SAPSII

39 (32, 47)

38 (31, 45)

44 (38, 51)

 < 0.001^c

SOFA

4 (2, 6)

4 (2, 6)

5 (4, 7)

0.007^c

Treatment, n (%)

IMV

240 (48.6)

193 (46.3)

47 (61.0)

0.002^b

Vasopressor

177 (35.8)

135 (32.4)

42 (54.5)

 < 0.001^b