Table 4 Sensitivity and sub group analysis of the pooled estimate of primary outcome

With fixed-model assumption (four studies)

I² value- 0%

P = 0.46

1.58 to 2.65

With random-model assumption (four studies)

I² value- 0%

P = 0.46

1.57 to 2.65

Fixed-model assumption with Ozlusus 2014 removed

I² value- 0%

P = 0.38

1.59 to 2.89

Random-model assumption with Ozlusus 2014 removed

I² value- 0%

P = 0.38

1.61 to 2.93

Fixed-model assumption with Pisacane 2005 removed

I² value- 0%

P = 0.44

1.66 to 3.07

Random-model assumption with Pisacane 2005 removed

I² value- 0%

P = 0.44

1.63 to 3.01

Fixed-model assumption with Sahip 2007 removed

I² value- 0%

P = 0.81

1.27 to 2.46

Random-model assumption with Sahip 2007 removed

I² value- 20%

P = 0.29

1.27 to 2.44

Fixed-model assumption with Su 2016 removed

I² value- 0%

P = 0.29

1.53 to 2.66

Random-model assumption with Su 2016 removed

I² value- 0%

P = 0.29

1.47 to 2.73