Table 2.

Quality assessment: internal validity of the included randomized trials

Ref.	Randomization allocation	Concealment of allocation	Blinding	Intention-to-treat analysis	Withdrawal and dropouts
COST 2007[16]	Yes	Not clear	Not clear	Yes	Clear report
Lacy 2008[15]	Yes	Adequate	Not clear	Yes	Clear report
COLOR 2009[14]	Yes	Not clear	Not clear	Yes	Clear report