Table 4 Result of individual variable meta-regression models for each stratified meta-analysis

Language of article:

 Chinese

6.0 (4.7-7.6), n = 70

0.060

60.1 (52.6-67.2), n = 69

0.018

4.2 (2.5-6.8), n = 18

0.402

 English

8.4 (2.7-23.0), n = 2

p = 0.956

57.9 (35.9-77.1), n = 2

p = 0.964

13.5 (10.9-16.6), n = 1

p = 0.823

Sample size:

 <500

4.8 (3.4-6.7), n = 50

0.178

59.8 (54.6-64.9), n = 53

-0.189

2.2 (1.2-4.1), n = 11

1.367

 ≥500

8.2 (5.6-11.8), n = 22

p = 0.561

60.3 (42.3-75.8), n = 18

p = 0.191

9.8 (5.7-16.2), n = 8

p = 0.029

Study locations*:

 HTA

17.5 (14.0-21.6), n = 27

-1.811

70.2 (62.6-76.8), n = 21

-0.335

8.0 (4.8-12.9), n = 10

-0.831

 LTA

2.4 (1.6-3.5), n = 45

p < 0.001

55.5 (46.4-64.2), n = 50

p = 0.017

2.5 (1.4-4.4), n = 9

p = 0.139

Sampling method:

 Cross-sectional

5.7 (4.3-7.4), n = 580

0.148

62.4 (54.2-69.9), n = 60

-0.275

4.6 (2.9-7.2), n = 19

-

 Others

8.3 (5.1-13.2), n = 14

p = 0.686

46.2 (36.3-56.5), n = 11

p = 0.112

-

-

Time period:

 2004–2006

8.0 (5.2-12.2), n = 16

-0.268

56.7 (47.0-65.8), n = 13

0.026

4.5 (0.3-40.4), n = 2

0.353

 2007–2010

5.5 (4.1-7.3), n = 56

p = 0.458

60.9 (52.1-69.0), n = 58

p = 0.879

4.4 (2.7-7.2), n = 17

p = 0.803