Table 2 Quality assessment of included studies

Author

Randomized adequately

Allocation concealment

Blinding

Completeness of follow-up

ITT analysis

Groups similar at baseline

Specific inclusion criteria

Modified Jadad score

Quality

Tan [21]

2

0

1

1

no

yes

yes

4

high

Sun [22]

2

0

1

1

no

yes

yes

4

high

Author

Representativeness of the exposed cohort

Selection of the nonexposed cohort

Ascertainment of exposure

Demonstration that outcome of interest was not present at start of study

Comparability of cohorts on the basis of the design or analysis

Assessment of outcome

Was follow-up long enough for outcomes to occur

Adequacy of follow up of cohorts

Quality

Erpicum [20]

1

1

1

1

1

1

1

1

high

Pan [23]

1

1

1

1

1

1

1

1

high