Is Screening Good For You?

More experts are questioning the practice of screening in particular cases – the testing of apparently healthy populations for underlying risk factors or undiagnosed conditions, such as some cancers, with a view to prevention or early treatment. Supporters of screening sometimes respond to their critics with more heat than light, but I don’t know who is right.

At first sight, screening may seem to be a sensible precaution, so why question it at all? Well, a lot depends on the prevalence of the risk factor or condition, the reliability of screening tests and the effects of early treatment. These are factors that need good and robust research. An epidemiologist friend once explained to me some of the maths of screening, and the results were surprising...