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Table 3 Interim decision rules

From: The Vitamin C, Thiamine and Steroids in Sepsis (VICTAS) Protocol: a prospective, multi-center, double-blind, adaptive sample size, randomized, placebo-controlled, clinical trial

Sample size Interim decision Condition for decision
N < 500 Futility May be recommended by DSMB
Expected success (mortality) PPmort (current N) > 0.90
Continue PPmort (current N) < 0.90
N ≥ 500 Futility PPVVFD (max N) < 0.10
Expected success (both endpoints) PPVVFD (current N) > 0.95 AND PPmort (current N) > 0.95
Expected success (VVFD only) PPVVFD (current N) > 0.95 AND PPmort (max N) < 0.10
Continue otherwise