Table 3 Level of evidence of the included studies and grade of recommendation

Pan A et al [14]

Interrupted time series

2+

C

Wang K-W et al [15]

Interrupted time series

2+

C

Cowling BJ et al [16]

Cohort Study

2-

C

Jüni P et al [17]

Cohort Study

2-

C

Wang J et al [18]

Longitudinal Study

2++

B

Cheng VC-C et al [19]

Cohort Study

2-

C

Thu TPB et al [20]

Longitudinal Study

2+

C

Seong H et al [21],

Cohort Study

2-

C

Lam HY et al [22]

Longitudinal Study

2+

C

Salvatore M et al [23]

Longitudinal Study

2+

C

Meo SA et al [24]

Cohort Study

2-

C

Xu T-L et al [25]

Longitudinal Study

2+

C

Zeng K et al [26]

Longitudinal study

2+

C

Wong CKH et al [27]

Longitudinal study

2+

C

Siedner MJ et al [28]

Longitudinal study

2+

C

Krishnamachari B et al [29]

Cohort Study

2+

C

Singh BB et al [30]

Longitudinal study

2-

C

Kepp KP et al [31]

Quasi experimental study

1+

A