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Table 2 Number and percentage of trials stopping for futility after 50%, 60%, 70%, 75%, 80% or 90% of patients recruited based on stopping boundaries of 20%, 30% or 40%

From: An investigation of the impact of futility analysis in publicly funded trials

 

Number (percentage) of trials

True successful result

CP stopping boundary 20%

CP stopping boundary 30%

CP stopping boundary 40%

Successful trial

Successful trial

Successful trial

Yes

No

Yes

No

Yes

No

Stop if futility analysis done

50% of patients

Stopped early

Yes

0

0

0

0

0

0

No

8 (28%)

21 (72%)

8 (28%)

21 (72%)

8 (28%)

21 (72%)

60% of patients

Stopped early

Yes

0

0

0

3 (12%)

0

8 (32%)

No

5 (20%)

20 (80%)

5 (20%)

17 (68%)

5 (20%)

12 (48%)

70% of patients

Stopped early

Yes

0

5 (21%)

0

11 (46%)

0

12 (50%)

No

5 (21%)

14 (58%)

5 (21%)

8 (33%)

5 (21%)

7 (29%)

75% of patients

Stopped early

Yes

0

7 (30%)

0

10 (43%)

0

14 (61%)

No

4 (17%)

12 (52%)

4 (17%)

9 (39%)

4 (17%)

5 (22%)

80% of patients

Stopped early

Yes

0

9 (41%)

0

11 (50%)

1 (5%)

14 (64%)

No

4 (18%)

9 (41%)

4 (18%)

7 (32%)

3 (14%)

4 (18%)

90% of patients

Stopped early

Yes

0

11 (55%)

0

12 (60%)

1 (5%)

15 (75%)

   

No

4 (20%)

5 (25%)

4 (20%)

4 (20%)

3 (15%)

1 (5%)

  1. CP, conditional power.