Table 4 Clinical and demographic characteristics of the patients (n = 1795)

Gender

Male

6

1082

1.419

0.236

Female

1

606

Age

>60

5

694

2.658

0.103

≤60

2

994

Hypertension

Yes

4

417

3.956

0.042*

No

3

1271

Diabetes

Yes

2

136

3.978

0.046*

No

5

1552

Smoking

Yes

5

1105

0.109

0.742

No

2

583

Drinking

Yes

6

975

2.24

0.13

No

1

713

Stage

I-II

0

825

6.681

0.01*

III-IV

7

863

ASA Class

I-II

2

820

1.123

0.289

III-IV

5

868

Preoperative radiotherapy

Yes

3

112

5.382

0.02*

No

4

1576

Previous chemotherapy

Yes

1

68

10.861

0.001*

No

6

1620

Tumor recurrence

Yes

1

156

3.106

0.078

No

6

1532

Neck dissection

Unilateral

4

153

3.441

0.179

Bilateral

2

1348

No

1

187

Airway management

Yes

5

1584

5.972

0.014*

No

2

104

Operation time (min)

>600

2

617

0.192

0.661

≤600

5

1071

Postoperative infection

Yes

4

306

7.147

0.007*

No

3

1382

Operation blood loss (ml)

>600

5

1025

0.335

0.562

≤600

2

663

Free flap repair

Yes

6

1304

0.16

0.68

No

1

334