Table 1.

Power analysis of TSUNAMI trial.

RR	Relative incidence reduction (1-RR)	Control incidence	Experimental incidence	Estimated sample size
0.5	0.5	0.26	0.13	290
0.6	0.4	0.26	0.156	476
0.67	0.33	0.26	0.1742	724
0.75	0.25	0.26	0.195	1304
0.8	0.2	0.26	0.208	2080

The control incidence was the mean basal incidence rate of the event in the control arm of all sites. The risk ratio (RR) was used to calculate the experimental incidence for power. The relative incidence reduction was expressed as 1-RR. The estimated sample size was the number of subjects to include in the study, with a ratio 1:1 between experimental arm and control arm.