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. 2008 Dec 4;337:a2299. doi: 10.1136/bmj.a2299

Table 2.

 Characteristics of published parallel group randomised trials

Characteristic No of trials (n=70)
Intervention:
 Drug 52
 Surgery/procedure 9
 Counselling/lifestyle 7
 Equipment 2
No of study groups:
 2 47
 3 15
 >3 8
Blinding:
 Blinded in some way 49
 None 13
 Unclear 8
Study centres:
 Single 24
 Multiple 46
Funding:
 Industry only 45
 Industry and non-industry 11
 Non-industry only 10
 None 3
 Unclear 1