Randomised controlled trials (RCTs) that compared a statin to control or to a less intensive statin regime were eligible for inclusion. Trials needed to have at least 100 participants and follow-up of at least six months. The outcomes of interest were ventricular tachyarrhythmia, cardiac arrest and sudden cardiac death. Authors were contacted for information where the outcomes of interest were not reported.
Some of the included studies were primary prevention studies. Others included people with evident cardiovascular disease (coronary heart disease, myocardial infarction, angina, stroke, heart failure), risk factors for heart disease (diabetes, hypertension) or kidney disease (renal failure, renal transplant). Mean ages ranged from 50 to 75 years. Between 30% and 94% of participants were men. Statins included pravastatin (10mg to 40mg), simvastatin (20mg to 40mg), atorvastatin (10mg to 80mg), lovastatin (20mg to 40mg), rosuvastatin (10mg to 40mg) and fluvastatin (40mg to 80mg). Controls included placebo, no treatment and usual care. In the studies that compared different dosing regimes, high doses were atorvastatin or simvastatin (80mg) compared to simvastatin (20mg) pravastatin (40mg) or atorvastatin (10mg to 40mg).
Two reviewers independently assessed studies for inclusion.