Table 2.

Quality assessment of included studies

Name of the author	Questions								Total score
	Selection questions				Comparability questions Q1	Outcome questions
	Q1	Q2	Q3	Q4		Q1	Q2	Q3
Timothy R. Card	A*	B*	D	A*	A*	D	A*	A*	6
Sutapa Ford	B*	C	B*	A*	C	C	A*	A*	5
Itai Ghersin	A*	A*	D	A*	C	D	A*	A*	5