Table 2

Reasons for excluding papers

Reason for exclusion
Number of papers

Before/after studies
17
Brief report given only
6
Case control study
5
Phase II trial (no control arm)
4
Randomisation not mentioned in full text
2
Allocated by patients' choice
1
Allocated by patients' economic status
1

Total
36

Zhang et al. Trials 2008 9:22   doi:10.1186/1745-6215-9-22