Twenty-three RCTs of statins were included. Ten studies (7 primary and 3 secondary prevention, n=22,909 participants) looked at pravastatin; four (all secondary prevention, n=5,160 participants) looked at simvastatin; eight (2 primary and 6 secondary prevention, n=17,029 participants) looked at lovastatin. Thirty-nine RCTs (4 primary and 35 secondary prevention, n=43,675 participants) looked at other cholesterol-lowering drugs.
Data from the 23 trials of statins demonstrated significant reductions in CHD events. In secondary prevention (prevention amongst people with evidence of cardiovascular disease) the relative reductions in total and CHD mortality were 21% (95% CI: 14, 27) and 26% (95% CI: 17, 34) respectively. There were similar reductions for non-fatal myocardial infarctions and greater reductions for combined end points (including revascularisation end points).
1. Efficacy of treatment with statins for primary prevention.
Total mortality: OR=0.79 (95% CI: 0.73, 0.86).
CHD mortality: OR=0.74 (95% CI: 0.66, 0.83).
Non-fatal MI: OR=0.70 (85% CI: 0.61, 0.80).
In primary prevention (amongst people with no sign of CHD) there were significant reductions for combined end points and non-fatal myocardial infarction, but not for total and CHD mortality. The primary prevention trials were too small to have adequate power to detect effects on mortality outcomes alone. Statins were effective across a wide range of levels of blood cholesterol, including levels considered normal in the UK.
Total mortality: OR=0.89 (95% CI: 0.73, 1.08).
CHD mortality: OR=0.76 (95% CI: 0.54, 1.06).
Non-fatal MI: OR=0.64 (85% CI: 0.53, 0.77).
Other treatments for primary prevention included advice on smoking cessation, nicotine replacement and antihypertensive drugs.
2. Efficacy of other treatments for secondary prevention.
Effects on cardiovascular mortality:
Tobacco smoking advice: RR=0.99 (95% CI: 0.98, 1.0).
Nicotine replacement: RR=0.98 (95% CI: 0.98, 0.99).
Aspirin: RR=0.98 (95% CI: 0.78, 1.18).
Anti-hypertensive drugs: RR=0.79 (95% CI: 0.71, 0.87) <60yrs; RR=0.75 (95% CI: 0.64, 0.88) >/=60yrs.
Statins: RR=0.68 (95% CI: 0.46, 1.00).
Other treatments considered for secondary prevention were advice on smoking cessation, aspirin, beta blockers, oily fish diet and Mediterranean diet.
Effects on cardiovascular mortality: Aspirin: RR=0.82 (95% CI: 0.76, 0.88).
Beta blockers: RR=0.78 (95% CI: 0.71, 0.87).
Statins: RR=0.74 (95% CI: 0.66, 0.83).
Tobacco smoking advice: RR=0.68 (95% CI: 0.57, 0.79).
Oily fish: RR=0.65 (95% CI: 0.5, 0.9).
Mediterranean diet: RR=0.24 (95% CI: 0.1, 0.8).
Except for smoking interventions, these treatments have numbers needed to treat that are broadly similar to those for statins.