Table 7.

Quality assessment of included studies

Study	Random selection in the population	Definition of inclusion and exclusion criteria	Report of losses to follow-up	Validated measurements	Statistical analysis	Risk of bias
Alkan et al. [2]	No	Yes	No	Yes	Yes	High
Durham et al. [21]	No	Yes	No	Yes	Yes	High
Landes et al. [22]	No	Yes	No	Yes	Yes	High
Gunbay et al. [23]	No	Yes	No	Yes	Yes	High
de Gijt et al. [24]	No	Yes	No	Yes	Yes	High
Ploder et al. [26]	No	Yes	No	Yes	Yes	High
Del Santo et al. [25]	No	Yes	No	Yes	Yes	High
Seeberger et al. [27]	No	Yes	No	Yes	Yes	High
Malkoc et al. [28]	No	Yes	No	Yes	Yes	High