Table 1.
Power for effects of a single agent on cancer in VITAL, a 2×2 factorial trial of 10,000 men aged ≥50 and 10,000 women aged ≥55, with 5 years of follow-up
| Observed RRa |
True RRb |
Total Cancer |
Cancer Mortality |
Colorectal Cancer |
Breast Cancer (Women) |
Prostate Cancer (Men) |
|---|---|---|---|---|---|---|
| 0.90 | 0.875 | 52.1 | - | - | - | - |
| 0.85 | 0.812 | 86.3 | - | - | - | - |
| 0.80 | 0.750 | 98.5 | 42.3 | 26.3 | 32.8 | 67.5 |
| 0.75 | 0.687 | 99.9 | 60.9 | 39.0 | 48.4 | 86.4 |
| 0.70 | 0.625 | >99.9 | 77.7 | 53.4 | 64.7 | 96.1 |
| 0.65 | 0.560 | >99.9 | 89.7 | 67.8 | 79.0 | 99.3 |
| 0.60 | 0.500 | >99.9 | 96.2 | 80.3 | 89.4 | 99.9 |
a
Observed RR=intent-to-treat RR, including noncompliant participants. Compliance is assumed to be 80%.
b
True RR=that with perfect compliance.
RR, rate ratio.