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Table 4 Required Sample Size for High-Risk Group Patients with Two Interim Analyses

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

Required Sample Size for High-Risk Group Patients with Two Interim Analyses
  Power = 80% Power = 90%
  P0 = 80% P0 = 70% P0 = 80% P0 = 70%
P1 N1 N2 Total N1 N2 Total N1 N2 Total N1 N2 Total
70% 171 342 513 NA NA NA 237 474 711 NA NA NA
65% 79 158 237 833 1666 2499 109 218 327 1155 2310 3465
60% 45 90 135 213 426 639 63 126 189 295 590 885
55% 30 60 90 96 192 288 41 82 123 133 266 399
50% 21 42 63 54 108 162 29 58 87 75 150 225
45% 15 30 45 35 70 103 21 42 63 48 96 144
40% 12 24 34 24 48 72 16 32 48 33 66 99
35% NA NA NA 17 34 51 NA NA NA 24 48 72
  1. P0: 30 days mortality rate in the standard arm. P1: 30 days mortality rate in the treatment arm
  2. N1: sample size for the standard care arm. N2: sample size for the treatment arm
  3. For 80% power: probability of rejection at each look: 1st look p < 0.002, futility look p > 0.835, 2nd look p < 0.014, futility look p > 0.312, final look p < 0.046
  4. For 90% power: probability of rejection at each look: 1st look p < 0.002, futility look p > 0.830, 2nd look p < 0.014, futility look p > 0.298, final look p < 0.046
  5. 1:2 randomization; ρ = 3.0
  6. Bold indicates recommended sample size with suggested parameters