Level 1: Likely reliable evidence
Statins reduce the incidence of MI and stroke in patients without cardiovascular disease (CVD), based on a systematic review of seven randomized trials with at least one year of follow-up (Arch Intern Med. 2006;166:2307-2313). More than 80% of the 42,848 participants did not have CVD; they were followed for mean 4.3 years. The mean age of patients in the trials ranged from 55-75 years, and the proportion of men ranged from 42%-100%.
Relative risk (RR) reductions were statistically significant for non-fatal MI (RR 0.68), coronary death or MI (RR 0.71), and stroke (RR 0.86). There was no significant difference in RR reductions for all-cause mortality (RR 0.92) or coronary mortality (RR 0.77). Absolute risk reductions varied depending on baseline risk: NNT was 133 for low-risk patients with annual coronary event rate 2%. Statins were considered cost-effective if 10-year risk was >20% and cost-ineffective if 10-year risk was <10%.
The cost-effectiveness is controversial if 10-year risk of coronary heart disease events is 10%-20%.