Table 2.
Declining Risk of Coronary Heart Disease According to Year of Follow-up for Women's Health Initiative Estrogen plus Progestin Risk of Coronary Heart Disease study.[8]
| Year of Follow-up |
No. of Cases of CHD (annualized percentage) |
No. of Cases (annualized percentage) |
Difference of Estrogen Plus Progestin Minus Placebo |
Hazard Ratio for CHD (95% CI) |
Significant |
|---|---|---|---|---|---|
| Estrogen plus progestin group | Placebo group | Plus or minus difference | |||
| 1 | 42 (0.50) | 23 (0.29) | + 19 | 1.81 (1.09 – 3.01) | YES |
| 2 | 38 (0.45) | 28 (0.35) | + 10 | 1.34 (0.82 – 2.18) | NO |
| 3 | 19 (0.23) | 15 (0.19) | + 4 | 1.27 (0.64 – 2.50) | NO |
| 4 | 32 (0.39) | 25 (0.32) | + 7 | 1.25 (0.74 – 2.12) | NO |
| 5 | 29 (0.41) | 19 (0.28) | + 10 | 1.45 (0.81 – 2.59) | NO |
| ≥ 6 | 28 (0.37) | 37 (0.56) | - 9 | 0.70 (0.42 – 1.14) | NO |
There is significantly increased risk in Year 1 compared with placebo, but less and nonsignificantly increased risk in Years 2 through 5. By Year 6 and beyond, the placebo increased and there was no increased risk (and there was actually an apparent risk reduction). This trend toward decreasing risk reduction was significant (z score for trend was – 2.36 (P = .02)