Table 1 Characteristics of 52 clinical trials that stopped for futility

Trial design

Parallel/ Factorial/ Cross-over/Cluster

50/0/0/2

Trial centres

Single

4

Multiple, national

22

Multiple, international

24

Unclear

2

Setting

Outpatient/ Inpatient / Acute care

33/ 11/ 8

Clinical area

Oncology

16

Cardiovascular research

9

Mental health

4

Obstetrics and gynaecology

4

Infectious diseases

3

Surgery

3

Gastrointestinal

3

Intensive care

3

Other^a

7

Type of intervention

Drug/ Surgical procedure/ Other

41/ 3 / 8

Type of control

Active intervention/ placebo/ no intervention

14/31/ 7

Trial sponsor

Industry/ Non-industry

21/31

Data safety and monitoring board

Yes/No

36/ 16

CONSORT mentioned

Yes/No

10/ 42

Published protocol

Journal publication/ Trial registry only /Not reported

4/ 22/ 26