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Table 6 Required Sample Size for Intermediate-Risk Group Patients with One Interim Analysis

From: Statistical design of Phase II/III clinical trials for testing therapeutic interventions in COVID-19 patients

Required Sample Size for Intermediate-Risk Group Patients with One Interim Analysis
Effect Size   α = 0.05 with 1:1 Group Ratio α = 0.05 with 1:2 Group Ratio
Power 80% 90% 80% 90%
10% N1 313 433 234 323
N2 313 433 468 646
Total 626 866 702 969
15% N1 139 192 104 143
N2 139 192 208 286
Total 278 384 312 429
20% N1 77 106 58 80
N2 77 106 116 160
Total 154 212 174 240
25% N1 48 67 37 50
N2 48 67 74 100
Total 96 134 111 150
30% N1 32 45 25 34
N2 32 45 50 68
Total 64 90 75 102
35% N1 23 31 18 25
N2 23 31 36 50
Total 46 62 54 75
40% N1 16 23 13 18
N2 16 23 26 36
Total 32 46 39 54
  1. N1: sample size for the standard care arm. N2: sample size for the treatment arm
  2. Response rate = 40%
  3. For 80% power: probability of rejection at each look: 1st look p < 0.006, futility look p > 0.709, final look p < 0.047
  4. For 90% power: probability of rejection at each look: 1st look p < 0.006, futility look p > 0.716, final look p < 0.047
  5. p = 2.0