Have statins been responsible for a major reduction in cardiovascular disease?

Question

Statins are a range of pharmaceuticals that inhibit the body's ability to produce "bad" cholesterol thereby reducing the amount in the blood. Lower LDL levels in the blood are known to be associated with lower levels of cardiovascular events such as heart attacks and strokes. The drugs have become one of the largest selling categories of pharmaceutical and are the most prescribed drug in the UK. According to The Telegraph:

The pills, which cost the NHS less than 10p per patient per day, are now the most commonly prescribed medication in Britain, with eight million people on some type of anti-cholestoral drug.

Some experts argue that statins have been a major contributor to the large reduction in mortality from cardio vascular disease that has been seen in recent decades. The Indian Express summarises the belied of some experts thus:

'Wonder drug' statins have slashed the number of deaths from heart attacks by half, saving millions of lives over the past decade, experts say.

There is some dissent, some challenging the effectiveness (not least because clinical trials have mostly used proxy endpoints rather than measuring the actual reduction in mortality: see this question Has the primary benefit of statins in reducing early deaths never been fully tested in comparative trials?), others challenging the use of drugs with significant known side effects when simple lifestyle interventions have much the same benefit (see this recent BMJ article comparing a statin a day to an apple a day). Others even argue that the epidemic of heart disease was declining rapidly and statins did little to affect the rate of decline.

The consensus seems to be leaning towards the miracle drug view that statins have saved many lives and could save more. Is this view right?

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Update

The benefits and harms from widespread use of Statins is still a significant topic in 2016 two years after this question was first asked here.

The BMJ and the Lancet (two of the world's top medical journals) have taken opposing views after the Lancet published a new review on the topic. The BMJ criticised the evidence used by the Lancet and wrote to England's Chief Medical Officer asking her to review the evidence to resolve the controversy (from the Daily Telegraph):

Dr Fiona Godlee has asked Dame Sally Davies to intervene after medical journal The Lancet published a review claiming the drugs were safe and effective and warning that their harms had been exaggerated.

The pro-statin experts claimed that the controversy had led many patients to stop taking the drugs and therefore:

...around 2,000 people may suffer a cardiovascular event such as a heart attack or stroke, experts have predicted.

If the benefit of statins is really this large, surely the evidence should be clear in the statistics for strokes and heart attacks? Is it?

Answer 1

See the Cochrane Review: Statins for the primary prevention of cardiovascular disease.

Their objective:

To assess the effects, both harms and benefits, of statins in people with no history of cardiovascular disease.

Selection criteria (they included all trials satisfying this criteria):

We included randomised controlled trials of statins versus placebo or usual care control with minimum treatment duration of one year and follow-up of six months, in adults with no restrictions on total, low density lipoprotein (LDL) or high density lipoprotein (HDL) cholesterol levels, and where 10% or less had a history of CVD.

Summary of included trials:

Eighteen randomised control trials (19 trial arms; 56,934 participants) were included. Fourteen trials recruited patients with specific conditions (raised lipids, diabetes, hypertension, microalbuminuria).

They summarize their main results as follows:

All-cause mortality was reduced by statins (OR 0.86, 95% CI 0.79 to 0.94); as was combined fatal and non-fatal CVD RR 0.75 (95% CI 0.70 to 0.81), combined fatal and non-fatal CHD events RR 0.73 (95% CI 0.67 to 0.80) and combined fatal and non-fatal stroke (RR 0.78, 95% CI 0.68 to 0.89). Reduction of revascularisation rates (RR 0.62, 95% CI 0.54 to 0.72) was also seen. Total cholesterol and LDL cholesterol were reduced in all trials but there was evidence of heterogeneity of effects. There was no evidence of any serious harm caused by statin prescription. Evidence available to date showed that primary prevention with statins is likely to be cost-effective and may improve patient quality of life. Recent findings from the Cholesterol Treatment Trialists study using individual patient data meta-analysis indicate that these benefits are similar in people at lower (< 1% per year) risk of a major cardiovascular event.

Highlights and re-phrasing

In the statin group, 1077/24,404 (4.4%) died. In the placebo group, 1223/23,562 (5.1%) died. In terms of confidence intervals, the all-cause mortality rate in the statin group is 0.86x the rate in the placebo group, with a 95% confidence interval of 0.79 to 0.94.

This means that in the population of people taking statins with no prior cardiovascular disease, the all-cause mortality rate is likely (with 95% confidence) 6-21% lower than in the population of people with no prior cardiovascular disease that are not taking statins.

Reference

Taylor, Fiona, K. Ward, T. H. Moore, M. Burke, and S. G. Davey. "Statins for the primary prevention of cardiovascular disease." Cochrane Database of Systematic Reviews 1 (2013). (Summary)