TABLE 4.

Quality appraisal for included studies

First author (year)	Appropriate randomization technique	Allocation concealment	Dropout rate below 20%	Potential confounders properly accounted for	Were eligibility clear
Watson (2012)	Yes	No	Yes	No	Yes
Yoo (2009)	Not clear	No	Yes	No	No
Piette (2012)	Yes	No	Yes	No	Yes
Orsma (2013)	Yes	No	Yes	Yes	Yes
Nolan (2012)	No	Yes	No	Yes	Yes
Friedman (1996)	Not clear	Not clear	Yes	Yes	Yes
Bennett (2012)	Not clear	No	Yes	Yes	Yes