Table 1. Study ratings using Buckley's criteria.

Abbreviations: Y: Yes; N: No; U: Unclear

 

Study

Clear research question

Subject group appro­priate for study

Reliable and valid methods

Complete-ness of data

Controlled for confound-ers if non-RCT design

Statistical methods appropriate

Data justifies conclusion drawn

Study could be replicated

Prosp-ective study

Relevant ethical issues address-ed

Triangul-ation of data

Total score

García Rodríguez et al., 1999 [32]

Y

Y

Y

Y/U

U

Y

Y

N

Y

N

U

6

Perveze et al., 2006 [33]

Y

Y

Y

Y/U

U

Y

Y

N

N

N/U

U

6

Paredes et al., 2007 [34]

U

Y

Y

Y/U

U

Y/U

Y

N

N

U

U

5

Kao et al., 2013 [35]

Y

Y

Y

U

U/N

Y

Y

N

Y

U

U

6

Chan et al., 2014 [36]

U

Y

Y

U

U/N

Y

Y

N

N

N

U

5

Gayam et al., 2018 [37]

Y

Y

Y

U

Y

Y

Y

N

N

N

U

6