Table 6

Sample size requirements for different scenarios. Sample size is calculated using 90% power and 5% alpha

Strategy
Intervention rate
Event rate in control arm of trial
Sample size (pts. screened) for relative risk of 0.75

Treat high-risk (risk 10% +)
52.60%
34.6%
1228 (2335)
Treat high-risk (risk 25% +)
27.20%
52.9%
624 (2294)
Treat high-risk (risk 50% +)
12.60%
74.6%
292 (2317)
Treat all
100.00%
20.0%
2504 (2504)

Vickers et al. Trials 2006 7:30   doi:10.1186/1745-6215-7-30