Table 1 Basic characteristics of patients from both training and validation cohort

Age (years)

70.50 ± 13.10

69.76 ± 13.48

0.490

BMI (kg/m²)

22.94 ± 3.21

22.90 ± 2.98

0.888

Sex

0.594

 Male

126 (20.5%)

59 (19.0%)

 Female

490 (79.5%)

252 (81.0%)

Reasons of operation

0.450

 FNF

197 (32.0%)

97 (31.2%)

 ONFN

257 (41.7%)

142 (45.7%)

 OAH

162 (26.3%)

72 (23.2%)

 Operation time (min)

91.62 ± 30.21

92.55 ± 31.68

0.977

 Intraoperative blood loss (mL)

118.84 ± 112.39

132.19 ± 126.91

0.444

Type of anesthesia

0.648

 GA

321 (52.1%)

167 (53.7%)

 CSEA

295 (47.9%)

144 (46.3%)

Smoking

0.347

 No

529 (85.9%)

274 (88.1%)

 Yes

87 (14.1%)

37 (11.9%)

Drinking

0.334

 No

535 (86.9%)

277 (89.1%)

 Yes

81 (13.1%)

34 (10.9%)

Hypertension

0.395

 No

275 (44.6%)

148 (47.6%

 Yes

341 (55.4%)

163 (52.4%

Diabetes

0.199

 No

485 (78.7%)

256 (82.3)

 Yes

131 (21.3)

55 (17.7%)

Cardiovascular disease

0.783

 No

541 (87.8%)

278 (89.4%)

 Yes

75 (12.2%)

33 (10.6%)

Cerebrovascular disease

0.276

 No

516 (83.8%)

269 (86.5%)

 Yes

100 (16.2%)

42 (13.5%)

Osteoporosis

0.517

 No

378 (61.4%)

184 (59.2%)

 Yes

238 (38.6%)

127 (40.8%)

TP (g/L)

65.70 ± 7.40

66.41 ± 7.19

0.164

ALB(g/L)

37.76 ± 4.99

38.19 ± 4.76

0.208

GLB (g/L)

27.82 ± 5.10

28.20 ± 5.33

0.330

SAA (mg/L)

81.70 ± 94.98

93.45 ± 108.59

0.056

IRON (μmol/L)

13.39 ± 12.30

13.10 ± 13.75

0.627

TIBC (μmol/L)

46.97 ± 9.33

47.20 ± 10.28

0.787

CRP (mg/L)

23.44 ± 32.77

27.54 ± 36.60

0.183

RBC (1,012/L)

3.94 ± 1.58

3.94 ± 0.67

0.450

Hb(g/L)

120.01 ± 20.13

121.47 ± 27.32

0.901

HCT (%)

36.04 ± 6.36

36.42 ± 5.85

0.395

MCV (fL)

93.30 ± 6.20

93.06 ± 6.81

0.823

MCH (pg)

31.11 ± 2.42

30.86 ± 2.78

0.519

MCHC (g/L)

333.08 ± 9.83

330.82 ± 11.68

0.055

Anemia

0.376

 No

381 (61.9%)

183 (58.8%)

 Yes

235 (38.1%)

128 (41.2%)