Table 4 Subgroup analysis results of UR incidence within 31 days after CRC surgery

Age

P = 0.0004

 < 60

5[16, 25, 27, 30, 31]

83

P < 0.001

Random

5.67% (3.75%− 7.60%)

 > 60

11[10, 16, 18, 25,26,27, 31, 32, 34,35,36]

100

P < 0.001

Random

11.48% (8.92%− 14.03%)

Gender

Random

0.87

Male

15[10, 16, 18, 25,26,27,28,29,30,31,32,33,34,35,36]

100%

P < 0.001

Random

11.80% (9.42%− 14.18%)

Female

15[10, 16, 18, 25,26,27,28,29,30,31,32,33,34,35,36]

100%

P < 0.001

Random

11.52% (9.19%− 13.86%)

Study Type

P < 0.001

Case–control

2[25, 27]

0

P = 0.81

Random

5.20% (4.20%− 6.21%)

Cohort study

13[10, 16, 18, 26, 28,29,30,31,32,33,34,35,36]

100

P < 0.001

Random

12.77% (10.32%− 15.22%)

Region

P = 0.004

Asia

4[25, 27, 30, 31]

83

P = 0.0006

Random

7.70% (4.86%− 10.54%)

Europe

3[10, 16, 33]

100

P < 0.001

Random

13.05% (1.43%− 24.66%)

North America

7[18, 28, 29, 32, 34,35,36]

92

P < 0.001

Random

11.62% (11.09%− 12.16%)

Oceania

1[26]

-

-

Random

14.98% (12.34%− 17.62%)

Sample size

P = 0.57

 ≤ 1000

7[25, 26, 28,29,30,31, 36]

89

P < 0.001

Random

12.54% (8.77%− 16.31%)

1000–10000

2[27, 32]

99

P < 0.001

Random

8.52% (1.92%− 15.12%)

 > 10,000

6[10, 16, 18, 33,34,35]

100

P < 0.001

Random

12.01% (8.52%− 15.50%)