Table 1 Univariable analysis for postoperative complications—OR (p value)

Age ≥ 65

0.8 (0.640)

0.7 (0.608)

1.0 (0.968)

1.2 (0.819)

0.5 (0.284)

2.2 (0.220)

2.8 (0.060)

3.1 (0.060)

4.0 (0.161)

1.8 (0.048)

1.6 (0.215)

Male sex

1.0 (0.948)

1.4 (0.611)

1.7 (0.054)

3.7 (0.195)

0.6 (0.461)

1.4 (0.585)

1.6 (0.292)

1.2 (0.670)

2.2 (0.330)

1.3 (0.364)

1.8 (0.221)

BMI ≥ 30

0.9 (0.882)

1.2 (0.781)

0.7 (0.145)

5.2 (0.040)

1.9 (0.419)

1.2 (0.746)

0.7 (0.559)

0.5 (0.333)

2.5 (0.255)

1.0 (0.928)

1.6 (0.255)

Smoker

1.2 (0.862)

1.5 (0.622)

1.3 (0.821)

1.0 (0.981)

2.1 (0.370)

3.7 (0.25)

3.4 (0.010)

2.4 (0.125)

1.0 (0.981)

1.8 (0.164)

2.3 (0.060)

Cardiovascular

2.1 (0.184)

1.0 (0.990)

1.2 (0.849)

1.8 (0.443)

0.8 (0.762)

0.8 (0.662)

2.0 (0.099)

3.6 (0.004)

1.2 (0.814)

1.3 (0.359)

1.1 (0.769)

Respiratory

1.2 (0.789)

1.0 (0.988)

0.8 (0.828)

0.7 (0.693)

1.3 (0.729)

0.9 (0.882)

1.3 (0.613)

0.2 (0.064)

0.5 (0.489)

1.2 (0.636)

0.4 (0.065)

Renal

0.7 (0.685)

1.0 (0.982)

2.1 (0.396)

0.7 (0.713)

2.6 (0.198)

2.7 (0.063)

1.7 (0.269)

2.8 (0.026)

2.1 (0.295)

1.8 (0.096)

1.7 (0.205)

Diabetes

(0.368)

(0.999)

1.1 (0.942)

0.9 (0.923)

1.9 (0.455)

3.7 (0.012)

1.4 (0.519)

1.3 (0.647)

2.9 (0.134)

0.9 (0.797)

1.1 (0.772)

Autoimmune

1.1 (0.901)

0.7 (0.696)

3.2 (0.174)

2.5 (0.269)

2.1 (0.374)

1.4 (0.590)

2.7 (0.036)

1.5 (0.505)

0.7 (0.785)

2.5 (0.025)

2.9 (0.010)

Malignant tumors

1.2 (0.849)

0.9 (0.926)

0.5 (0.519)

(0.999)

(0.999)

1.6 (0.674)

0.5 (0.209)

1.0 (0.953)

0.9 (0.330)

1.2 (0.702)

2.2 (0.290)

Rectal tumous

0.6 (0.528)

0.4 (0.333)

0.8 (0.181)

(0.354)

1.2 (0.862)

1.1 (0.802)

0.8 (0.753)

2.3 (0.071)

(0.214)

0.6 (0.101)

0.4 (0.080)

Open approach*

2.8 (0.070)

1.0 (0.952)

2.1 (0.376)

3.3 (0.108)

0.6 (0.621)

3.7 (0.010)

2.7 (0.024)

1.8 (0.255)

3.6 (0.050)

3.2 (0.001)

2.0 (0.072)

Hemoglobin < 10 g/dl

2.8 (0.093)

0.6 (0.665)

1.2 (0.893)

4.7 (0.033)

3.7 (0.064)

0.9 (0.873)

0.8 (0.742)

0.6 (0.478)

3.1 (0.108)

2.3 (0.040)

1.6 (0.299)

WCC < 4× 10⁹/L

1.0 (0.721)

1.0 (0.755)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.498)

(0.999)

WCC > 11× 10⁹/L

1.3 (0.786)

(0.999)

(0.999)

2.8 (0.345)

(0.999)

4.4 (0.025)

3.9 (0.024)

3.1 (0.090)

(0.999)

6.2 (0.008)

8.3 (0.000)

Platelet < 150× 10⁹/L

(0.999)

(0.999)

10.3 (0.018)

8.5 (0.032)

(0.999)

3.3 (0.277)

12.9 (0.001)

2.5 (0.402)

(0.999)

1.6 (0.621)

2.9 (0.225)

Platelet > 400× 10⁹/L

1.2 (0.855)

(0.999)

(0.999)

2.5 (0.394)

5.4 (0.030)

4.0 (0.038)

1.3 (0.743)

3.0 (0.104)

15.8 (0.000)

6.9 (0.005)

6.8 (0.000)

Lymphocytes < 1× 10⁹/L

3.1 (0.048)

2.0 (0.315)

2.3 (0.324)

1.9 (0.462)

0.6 (0.677)

0.6 (0.548)

1.5 (0.411)

1.5 (0.471)

1.3 (0.740)

1.4 (0.343)

1.9 (0.105)

Neutrophils < 2× 10⁹/L

1.0 (0.719)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.493)

(0.999)

Neutrophils > 8× 10⁹/L

1.1 (0.913)

(0.999)

(0.999)

2.3 (0.437)

2.0 (0.529)

5.7 (0.003)

4.5 (0.006)

1.5 (0.625)

1.7 (0.615)

7.4 (0.003)

5.8 (0.000)

PLR < 61

1.0 (0.799)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

PLR > 239

2.3 (0.146)

1.1 (0.915)

1.3 (0.790)

1.0 (0.997)

2.6 (0.170)

1.6 (0.800)

0.7 (0.595)

0.8 (0.715)

3.3 (0.066)

1.7 (0.080)

2.1 (0.041)

NLR < 0.83

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

(0.999)

NLR > 3.92

1.5 (0.523)

2.4 (0.172)

4.8 (0.051)

0.9 (0.908)

1.4 (0.664)

3.2 (0.020)

2.3 (0.044)

1.8 (0.198)

3.0 (0.096)

3.4 (0.000)

3.9 (0.000)

CRP ≥ 5 mg/L

2.2 (0.356)

1.6 (0.593)

5.7 (0.079)

(0.052)

(0.024)

15.4 (0.001)

4.5 (0.007)

7.6 (0.003)

(0.052)

16.9 (0.000)

20.5 (0.000)

CRP ≥ 10 mg/L

2.4 (0.281)

1.0 (0.008)

10.1 (0.014)

1.1 (0.002)

10.1 (0.014)

16.9 (0.001)

10.4 (0.000)

3.6 (0.021)

1.1 (0.002)

106.3(0.000)

63.3 (0.000)

CEA ≥ 3 ng/mL

1.1 (1.000)

0.2 (0.123)

0.3 (0.373)

1.1 (0.872)

1.5 (0.575)

1.6 (0.406)

1.0 (0.935)

1.5 (0.425)

3.0 (0.254)

1.9 (0.036)

1.3 (0.551)

T stage ≥ 4

2.3 (0.213)

(0.999)

4.7 (0.073)

1.1 (0.931)

(0.600)

1.0 (0.987)

1.1 (0.876)

2.7 (0.076)

2.0 (0.413)

2.6 (0.033)

1.6 (0.328)

Node positive

0.3 (0.123)

2.2 (0.254)

2.6 (0.294)

2.3 (0.276)

1.0 (0.997)

0.8 (0.725)

0.8 (0.672)

1.2 (0.667)

2.2 (0.254)

0.9 (0.594)

1.0 (0.897)

Moderate/poorly differentiated

3.4 (0.220)

0.6 (0.437)

0.4 (0.351)

1.8 (0.587)

0.9 (0.876)

0.8 (0.705)

1.3 (0.670)

0.4 (0.034)

0.6 (0.437)

1.0 (0.926)

0.8 (0.628)