HMG-CoA reductase inhibitors, or statin drugs, effectively reduce cholesterol levels. A reduction in cholesterol levels is known to decrease the risk of coronary heart disease, but the effect of cholesterol reduction on stroke risk and mortality is unclear. Hebert and colleagues gathered data from trials of statin drugs to determine if the risk of stroke and mortality is reduced with the use of these agents.

A literature search identified 16 clinical trials of statin drugs in which data for death and stroke were reported. Some of the studies were primary prevention trials and others were secondary prevention trials. Most included patients with elevated cholesterol levels, although one study evaluated patients with normal levels.

Treatment ranged from eight weeks to more than five years. Mean baseline cholesterol levels in the clinical trials ranged from 203 to 296 mg per dL (5.3 to 7.7 mmol per L). Drugs that were studied included lovastatin (six studies), pravastatin (eight studies) and simvastatin (two studies). No significant differences in cholesterol-lowering effects were found among these drugs.

There were 454 strokes and 1,175 deaths during the course of the studies, which included approximately 29,000 participants. Treatment with statin drugs was associated with a statistically significant 29 percent reduction in fatal and nonfatal strokes. The treatment groups also showed a significantly lower rate of cardiovascular disease deaths and deaths resulting from all causes than the placebo groups. Total mortality was reduced 22 percent in the treatment groups, compared with the placebo groups.

The authors conclude that cholesterol reduction with statin drugs reduces stroke, deaths that are due to cardiovascular disease and overall mortality. Treatment with these agents was not associated with an increase in noncardiovascular disease deaths or the incidence of cancer.