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Table 3. Primary Prevention Trials of Drug Therapy: Results*

Study details LRC (34) Helsinki (35) WOSCOPS (36) AFCAPS(37)
Year 1984 1987 1995 1998
Main outcome Nonfatal MI, CHD death Nonfatal MI, CHD death Nonfatal MI, CHD death Nonfatal MI, CHD death, unstable angina
Cumulative event ratea 8.1/9.8 2.73/4.14 5.5/7.9 3.4/5.45
I/C (5.5/6.6)b     1.65/2.9c
ARR 1.7 (1.1)b 1.41 2.4 2.05 (1.25)c
NNT for 5 yearse (91)b 71 42 49 (80)c
RRR (%) 19 34 31 37
(95% CI) (3-32)d (8-53) (17-43) (21-50)

[a] Event rates are cumulative incidence in percentages for the event over the study; I, intervention, C, control.
[b] Adjusted 5-year outcomes for LRC.
[c] Unstable angina excluded in results.
[d] CI for LRC was 90%.
[e] NNT for 5 years to prevent 1 CHD event.

*LRC, Lipids Research Council; HHS, Helsinki Heart Study; WOSCOPS, West of Scotland Coronary Prevention Study; AFCAPS, Air Force/Texas Coronary Atherosclerosis Prevention; MI, myocardial infarction; CHD, coronary heart disease; ARR, absolute risk reduction; NNT, numbers needed to treat; RRR, relative risk reduction; CI, confidence interval.

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