Coronary artery disease: screen or treat?

The central argument of The Widowmaker, a controversial US documentary attacking interventional cardiologists,1 is that computed tomographic (CT) calcium scoring could be used to screen the apparently healthy population and prevent thousands of deaths from heart attack. However, screening is not prevention; it is a method of rationing preventive interventions that would be too unpleasant or expensive to offer to all. The scans themselves are not treatment; they do not prolong lives.

Coronary artery disease is unusual in that effective preventive treatment has been established by randomised controlled trials. For example, statins under blinded evaluation seem to cause no more symptoms than placebo2 and reduce rates of myocardial infarction or death from coronary disease—for example, by 31% in middle aged men with high cholesterol.3 Their five year event rate was reduced from 7.9% to 5.5%, an absolute risk reduction of 2.4%. The limited period of randomisation prevents trials showing effects of a lifetime of therapy. Mathematical studies can overcome this by calculating average expected lifespan extension, which is about nine months for 50 year olds with the distribution of risk …