Examples
EVENTS, EVENT
If we assume 185 patients are randomised to the control arm and 185 patients to the experimental arm, and that there is 10% attrition, as hypothesised in the sample size calculation, we will observe the outcome for 166 patients in each arm. We consider three possible scenarios:As expected (event risks 12% (C) and 12% (E)): 20 events are observed for both arms, i.e. participants meeting primary endpoint of confirmed viral rebound (2 consecutive HIV RNA ≥ 50 c/mL), for a 12.0% control and experimental arm event risk. This is exactly as assumed in the sample size calculations.Slightly lower control risk (event risks 8% (C) and 11% (E)): 14 events (8.4%) are observed in the control arm, and 19 (11.4%) in the experimental arm.Very low (event risks 1% (C) and 5% (E)): only 2 events (1.2%) are observed in the control arm, and 9 (5.4%) in the experimental arm.Table Finally, example 3 is the one leading to the biggest differences between the method keeping the non-inferiority margin fixed and the other four, which are using the SAFE frontier. All methods using the SAFE frontier lead to similar results (large 