Table 3

Disease area of included trials

Disease area
Number of papers
Percent

Digestive system diseases
50
16.3
Circulatory system diseases
48
15.6
Tumours*
42
13.7
Urogenital system diseases
37
12.1
Nervous system diseases
16
5.2
Motor system diseases
16
5.2
Healthy population
15
4.9
Respiratory system diseases
15
4.9
Endocrine system diseases
12
3.9
Immune system diseases
9
2.9
Others
47
15.3

Total
307
100.0

*All types/locations of tumours

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