Table 4. Reasons and strategies for trial redesign.
Characteristics of trials with major redesign (n = 27) | Frequency of redesigned trial characteristic by accrual status at trial closure | |
---|---|---|
| ||
Sufficient | Insufficient | |
Primary reason for redesign | ||
Slow accrual | 3 | 4 |
Fast accrual | 3 | 0 |
New data | 6 | 1 |
Lower than predicted event rate | 3 | 1 |
Interim analysis results | 1 | 0 |
Different than anticipated trial coursea | 4 | 0 |
Unknown | 0 | 1 |
Accrual status at time of redesign | ||
Slower than projected | 5 | 7 |
On projected target | 10 | 0 |
Faster than projected | 5 | 0 |
Primary redesign strategyb | ||
Decrease sample size | 2 | 1 |
Increase sample size | 13 | 0 |
Alter endpoint | 1 | 0 |
Recalculate type 1 error from two- to one-sided | 1 | 0 |
Modify eligibility criteria | 0 | 2 |
Add/delete treatment arm | 3 | 1 |
Modify treatment arm | 0 | 1 |
Change randomization to 2:1 | 0 | 1 |
Includes different than anticipated treatment effects, treatment compliance, patient eligibility, or cooperative group participation.
One trial not included here closed and reopened as a different trial as a response to poor accrual.