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Table 1 Proportion of trials showing significant improvement with the experimental treatment (“standard” and “changing with time” cases)

From: Evaluation by simulation of clinical trial designs for evaluation of treatment during a viral haemorrhagic fever outbreak

  Design pC = 0.50 pC = 0.35 pC = 0.75
∆ = 0.20 ∆ = 0.10 ∆ = 0 ∆ = − 0.10 ∆ = 0.20 ∆ = 0 ∆ = 0 ∆ = − 0.10
Standard F1 0.896 0.351 0.025 0.0002 0.120 0.000 0.985 0.662
S1 0.893 0.339 0.024 0.0003 0.115 0.0001 0.982 0.657
F2 0.897 0.347 0.024 0.0001 0.887 0.025 0.025 0.0001
S2 0.904 0.339 0.025 0.0004 0.883 0.025 0.024 0.0002
Changing
with time
F1 0.964 0.536 0.069 0.0011 0.241 0.0001 0.997 0.823
S1 (a) 0.944 (0) 0.520 (0) 0.062 (0) 0.0008 (0) 0.229 (0) 0 (0) 0.991 (0) 0.796 (0)
F2 0.926 0.370 0.025 0.0002 0.875 0.023 0.025 0.0001
S2 (a) 0.958 (0.0007) 0.390 (0.0001) 0.024 (0) 0.0004 (0) 0.880 (0) 0.025 (0) 0.015 (0.11) 0 (0)
  1. In bold, type-I-errors maintained in [0.024;0.026]
  2. Abbreviations: pC indicates control survival rate; ∆: simulated survival rate difference; F1: fixed single-arm design; S1: group-sequential single-arm design; F2: fixed two-arm design; S2: group-sequential two-arm design; Standard: specific case with a fixed control survival rate; Changing with time: specific case with an increase of the control survival rate over time
  3. (a): Proportion of significant tests with proportion of inconclusive group-sequential trials for “changing with time” case