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Table 4 Impact on patients recruited and trial duration of stopping accrual at a set timepoint

From: Issues in applying multi-arm multi-stage methodology to a clinical trial in prostate cancer: the MRC STAMPEDE trial

  Median Arms accruing at Activity Stage   Total Differences b in
Pts/yr Median FFS (m) Median OS (m) 1 2 3 4 Year accrual stopped Pts Time (m) Total pts Time (m)
No arms stop early
500 24 48 6 6 6 6 Uncappedc 3411 82 0 0
500 24 48 6 6 6 6 7 3411 82 0 0
500 24 48 6 6 6 6 6 3000 83 -411 1
500 24 48 6 6 6 6 5 2500 89 -911 7
One arm is dropped after each Activity Stage
500 24 48 6 5 4 3 Uncappedc 3133 75 0 0
500 24 48 6 5 4 3 7 3133 75 0 0
500 24 48 6 5 4 3 6 3000 75 -133 0
500 24 48 6 5 4 3 5 2500 80 -633 5
Dropped to 2 arms after Activity Stage I
500 24 48 6 2 2 2 Uncappedc 2738 66 0 0
500 24 48 6 2 2 2 7c 2738 66 0 0
500 24 48 6 2 2 2 6 2738 66 0 0
500 24 48 6 2 2 2 5 2500 66 -162 0
Dropped to 2 arms after Activity Stage II
500 24 48 6 6 2 2 Uncappedc 2983 72 0 0
500 24 48 6 6 2 2 7c 2983 72 0 0
500 24 48 6 6 2 2 6 2983 72 0 0
500 24 48 6 6 2 2 5 2500 75 -483 3
One arm dropped after each Activity Stage & survival is longer
500 24 60 6 5 4 3 Uncapped 3397 82 0 0
500 24 60 6 5 4 3 7c 3397 82 0 0
500 24 60 6 5 4 3 6 3000 83 -397 1
500 24 60 6 5 4 3 5 2500 91 897 91
One arm is dropped after each Activity Stage & accrual is slower
350 24 48 6 5 4 3 Uncapped 2702 93 0 0
350 24 48 6 5 4 3 7 2450 94 -252 1
350 24 48 6 5 4 3 6 2100 101 -602 8
350 24 48 6 5 4 3 5a n/a n/a n/a n/a
  1. Uncapped means that accrual continues until the point of maturity.
  2. a Model not provided because Efficacy Stage III would not have been completed by 5 years
  3. b Differences compared with the uncapped model with the same parameters
  4. c Recruitment would have been completed at sooner time point ie another model stops accrual sooner eg the first row shows uncapped accrual to be the same as accrual to 7 years because the accrual-to-7-years model stops accrual just before 7 years