Table 1 Baseline characteristics and surgery-related variables between the study groups before and after sIPTW

Male

600 (66.0%)

617 (56.7%)

0.192

552 (61.0%)

658 (60.6%)

0.009

Age, years

63 (56–70)

65 (59–72)

0.240

64 (58–71)

65 (58–71)

0.006

Body mass index, kg/m²

23.7 (21.6–25.7)

22.8 (21.0–24.8)

0.241

23.3 (21.2–25.4)

23.2 (21.3–25.1)

0.010

Current smoker

155 (17.1%)

142 (13.1%)

0.112

132 (14.7%)

159 (14.6%)

0.001

Neoadjuvant chemotherapy

67 (7.4%)

80 (7.4%)

0.001

65 (7.1%)

78 (7.2%)

0.003

Neoadjuvant radiotherapy

31 (3.4%)

31 (2.8%)

0.032

28 (3.1%)

35 (3.2%)

0.003

Preoperative biliary drainage

247 (27.2%)

253 (23.3%)

0.090

229 (25.3%)

272 (25.0%)

0.008

Pathology

0.254

0.017

 Pancreatic cancer

315 (34.7%)

494 (45.4%)

360 (39.8%)

439 (40.4%)

 Distal CBD cancer

216 (23.8%)

189 (17.4%)

181 (20.1%)

216 (19.9%)

 Ampulla of Vater cancer

193 (21.2%)

184 (16.9%)

173 (19.2%)

206 (19.0%)

 Duodenal cancer

20 (2.2%)

32 (2.9%)

23 (2.5%)

28 (2.6%)

 Neuroendocrine tumor

72 (7.9%)

78 (7.2%)

68 (7.5%)

81 (7.5%)

 Benign diseases

53 (5.8%)

55 (5.1%)

52 (5.7%)

61 (5.7%)

 Others

40 (4.4%)

56 (5.1%)

46.5 (5.2%)

53.6 (4.9%)

Preoperative temperature, ℃

36.5 (36.2–36.7)

36.4 (36.1–36.6)

0.113

36.4 (36.2–36.7)

36.4 (36.2–36.7)

0.011

PPPD (vs. Whipple’s operation)

732 (80.5%)

805 (74.0%)

0.156

696 (77.1%)

833 (76.7%)

0.008

Robot-assisted (vs. open)

107 (11.8%)

96 (8.8%)

0.097

93 (10.3%)

111 (10.2%)

0.003

Trans-anastomotic pancreatic ductal stent

884 (97.2%)

1016 (93.4%)

0.184

863 (95.6%)

1033 (95.2%)

0.019

Fistula risk score (0–10)

5 (3–6)

5 (3–6)

0.282

5 (3–6)

5 (3–6)

0.011

Operation time, hour

5.2 (4.3–6.2)

5.2 (4.2–6.1)

0.086

5.2 (4.3–6.1)

5.2 (4.2–6.2)

< 0.001

Estimated blood loss, mL

400 (250–600)

350 (200–500)

0.188

400 (250–550)

400 (250–550)

0.021

Intraoperative colloid, mL

0 (0–500)

0 (0–500)

0.084

0 (0–500)

0 (0–500)

0.001

Intraoperative crystalloid, mL

2600 (2000–3300)

2400 (1850–3100)

0.146

2500 (2000–3200)

2400 (1900–3200)

0.007

Intraoperative transfusion

140 (15.4%)

135 (12.4%)

0.087

128 (14.2%)

152 (14.0%)

0.005

Intraoperative severe hypothermia

50 (5.5%)

70 (6.4%)

0.039

55 (6.0%)

66 (6.1%)

0.002

Year of surgery

0.159

0.009

 2007–2010

200 (22.0%)

259 (23.8%)

208 (23%)

252 (23.2%)

 2011–2013

205 (22.6%)

244 (22.4%)

199 (22%)

241 (22.2%)

 014–2016

179 (19.7%)

267 (24.5%)

208 (23%)

246 (22.7%)

 2017–2019

325 (35.8%)

318 (29.2%)

289 (32%)

346 (31.9%)