Table 3 Cox proportional hazard regression analysis of the risk of all-cause death in patients with oropharyngeal squamous cell carcinoma patients receiving concurrent chemoradiotherapy, stratified by the AJCC clinical stage

Pre-CCRT PET-CT (No Pre-CCRT PET-CT as reference)

1.19

(0.90–1.43)

0.1566

0.75

(0.87–0.94)

0.0236

Sex

 Female

1

 < 0.0001

1

 < 0.0001

 Male

3.14

(1.98–4.98)

2.26

(1.80–2.82)

Age (years)

 ≤ 40

1

0.0120

1

0.0251

 41–50

1.01

(0.52–1.25)

1.02

(0.75–1.10)

 51–60

1.07

(0.46–1.15)

1.05

(0.70–1.12)

 61–70

1.09

(0.47–1.27)

1.15

(0.69–1.24)

 > 70

1.16

(1.07–1.89)

1.23

(1.08–1.55)

Differentiation

 Well

1

0.0453

1

 < 0.0001

 Moderate

1.01

(1.00–1.25)

1.03

(1.01–1.19)

 Poor

1.15

(1.02–1.63)

1.19

(1.13–1.44)

AJCC clinical stages

 I

1

0.5363

–

–

 II

1.13

(0.86–1.50)

–

–

 III

–

–

1

0.2310

 IV

–

–

1.10

(0.92–1.35)

CCI scores

 0

1

 < 0.0001

1

 < 0.0001

 1

1.32

(1.06–1.65)

1.07

(1.03–1.20)

 2 + 

1.80

(1.43–2.26)

1.43

(1.27–1.62)

Diagnosis year

 2008–2010

1

0.1471

1

0.1734

 2011–2014

0.91

(0.74–1.13)

0.99

(0.88–1.11)

 2015–2018

0.72

(0.58–1.11)

0.84

(0.74–1.04)

Hospital volume

 High patient volume

1

0.0023

1

 < 0.0001

 Low patient volume

1.34

(1.11–1.62)

1.27

(1.16–1.39)