Table 2. Quality assessment for non-randomized trials.

Quality assessment for non-randomized trials	Hey 2013	Liu 2012	Shen 2013	Shin 2009
A clearly stated aim	2	2	2	2
Inclusion of consecutive patients	2	1	1	1
Prospective data collection	2	2	2	2
Endpoints appropriate to the aim of the study	1	1	1	1
Unbiased assessment of the study endpoint	0	0	0	1
A follow-up period appropriate to the aims of study	2	2	2	2
Less than 5% loss to follow-up	2	2	2	2
Prospective calculation of the sample size	0	0	0	0
An adequate control group	2	1	2	1
Contemporary groups	1	0	1	1
Baseline equivalence of groups	2	2	2	2
Adequate statistical analyses	2	2	2	1
Total score	16	15	17	15