Sample sizes for superiority study designs. The hypothesis is that the new modulator is more efficacious than a comparator (either placebo or an active comparator)
| Anticipated FEV1 treatment effect: New modulator−comparator (%) | SD of the change in FEV1 % predicted* | Sample size per group† | |
|---|---|---|---|
| Scenario A | 3 | 7.3 | 125 |
| Scenario B | 5 | 7.3 | 45 |
| Scenario C | 10 | 7.3 | 12 |
Scenarios estimate the sample size for a 1:1 randomised study with a primary endpoint of absolute change in FEV1% predicted.
*SDs approximated from the 6-month changes in FEV1 observed in previous trials.16 ,21
†Estimated using a two-sample t test assuming 90% power and a two-sided 0.05 level of significance.