Table 1 Summary of characteristics of the included studies

 Li

(2019) [5]

China

A hospital affiliated with Anhui Medical University

Cohort study

Median 21

206

IR 28/62

ER37/79

IR

Mean 40.2

ER

Mean 37.8

IR 62/90

ER 97/116

IR 53/90

ER 89/116

Not clear

IR 57/90

ER 85/116

IR 12/90

ER 31/116

Not clear

 Taylor

(2018) [6]

USA

A Health System from University of Virginia

Cohort study

2

108

Not clear

Not clear

IR 15/34

ER 49/74

Not clear

IR 7/28

ER 8/69

Not clear

IR 13/34

ER 16/74

Not clear

 Kim

(2015) [7]

Korea

A hospital and research

institute associated with Yonsei University College of Medicine

Cohort study

Mean

57.6

1089

464/625

Mean 43.4

IR 773/826

ER 258/263

IR 302/354

ER 129/143

IR 82/723

ER 36/235

Not clear

IR 344/826

ER 156/263

IR 22/826

ER 11/263

 Kawamata

(2005) [8]

Japan

A Neurological Institute associated with Tokyo Women’s Medical University

Cohort

study

IR

Mean 25.2

ER

Mean 38.0

48

IR 8/10

ER11/19

IR

Mean 44.9

ER

Mean 49.8

Not clear

IR 11/18

ER 27/30

IR 1/18

ER 2/30

IR 0/18

ER 0/30

Not clear

Not clear

 Kinoshita

(2016) [9]

Japan

A hospital associated with Hiroshima

University

Cohort

study

3

132

IR 33/34

ER33/32

IR

Median 61

ER

Median 65

Not clear

Not clear

Not clear

IR 10/67

ER 15/65

IR 16/67

ER 26/65

IR 1/67

ER 0/65

 Qu

(2011) [10]

China

A third grade class-A hospital affiliated with Shandong University

Cohort

study

Median 39

142

IR 30/34

ER35/43

Mean 37 ± 1.2

IR 44/64

ER 71/78

IR 45/64

ER 72/78

IR 4/64

ER 8/78

IR 16/64

ER 21/78

Not clear

IR 2/64

ER 6/78

 Xie

(2016) [11]

China

A hospital and Medical Research Center affiliated with Fudan University

Cohort

study

12

43

IR 9/13

ER11/10

IR 47.86

 ± 11.62

ER 49.19

 ± 12.39

IR 12/22

ER 18/21

IR 12/22

ER 18/21

IR 3/22

ER 1/21

IR 6/22

ER 3/21

IR 8/22

ER 8/21

IR 2/22

ER 4/21