Fifteen studies (63,410 participants) were included. Of these 4 studies (14,566 participants) were primary prevention, 10 studies (28,308 participants) were secondary prevention and one study (20,536 participants) was mixed (primary and secondary prevention).
Tests for heterogeneity showed little variability between studies so fixed-effect analyses were reported. Not all studies reported on all outcomes.
Primary prevention.
The use of statins reduced the risk of cardiovascular mortality (RR 0.66, 95% CI: 0.49, 0.90, P=0.0082) and of having a coronary event (RR 0.67, 95% CI: 0.58, 0.77, P<0.0001). There was no difference in non-cardiovascular mortality between the statins and placebo groups (RR 1.03, 95% CI: 0.80, 1.33, P=0.8026). There was no evidence of an effect on fatal stroke, nonfatal stroke or total stroke. The effect on all-cause mortality was non significant (RR 0.86, 95% CI: 0.72, 1.04, P=0.1303).
Secondary prevention.
The use of statins reduced the risk of a coronary event (RR 0.74, 95% CI: 0.69, 0.79, P<0.0001), CVD mortality (RR 0.76, 95% CI: 0.69, 0.84, P<0.0001) and all-cause mortality (RR 0.80, 95% CI: 0.74, 0.87, P<0.0001). The risks of nonfatal stroke and total stroke (fatal and nonfatal) were also reduced. There was no evidence of an effect on non-CVD mortality (RR 0.88, 95% CI: 0.75, 1.02, P=0.1677) or fatal stroke (RR 0.99, 95% CI: 0.67, 1.48, P=0.9832).
Primary, secondary and mixed studies analysed together.
The use of statins reduced CVD mortality (RR 0.78, 95% CI: 0.73, 0.84, P<0.0001) and coronary events (RR 0.73, 95% CI: 0.68, 0.77, P<0.0001), nonfatal stroke (RR 0.74, 95% CI: 0.67, 0.82, P=0.0001), total stroke (fatal and nonfatal) (RR 0.94, 95% CI: 0.86, 1.03, P=0.1677) and all-cause mortality (RR 0.77, 95% CI: 0.70, 0.84, P<0.001). The effect on non-CVD mortality or fatal stroke did not reach statistical significance (P=0.1677 and P=0.1912, respectively). Statin use was associated with a 22% reduction in total cholesterol, a 29% reduction in LDL cholesterol, a 12% reduction in triglycerides and a 6% increase in HDL cholesterol. Different statins appeared to have similar effects on cholesterol levels. The results were not altered when individual studies were removed from the analyses.