Sometimes people take percentages too seriously.
Case 1: Statins, a class of drugs that lower cholesterol levels in people with or at risk of cardiovascular disease, seem to be emerging as the next wonder drug that everyone should be taking. Unfortunately, the improvement seems to be an improvement over something that is already pretty close to zero.
Is this true? Yes. Those are the figures on risk, expressed as something called the “Relative Risk Reduction“. It is the biggest possible number for expressing the change in risk. But 54% lower than what? This was a trial looking at whether it is worth taking a statin if you are at low risk of a heart attack (or a stroke), as a preventive measure: it is a huge market – normal people – but these are also people whose baseline risk is already very low.
If you express the exact same risks from the same trial as an “Absolute Risk Reduction“, suddenly they look a bit less exciting. On placebo, your risk of a heart attack in the trial was 0.37 events per 100 person years, and if you were taking rosuvastatin, it fell to 0.17 events per 100 person years. 0.37 to 0.17. Woohoo. And you have to take a pill every day. And it might have side effects.
Case 2: Some people are hyping the efficiency of Medicare, a supposed “miracle of low overhead and a model, despite all the fraud and abuse, of what government can do right.” Unfortunately, there’s a catch:
But here’s the catch: because Medicare is devoted to serving a population that is elderly, and therefore in need of greater levels of medical care, it generates significantly higher expenditures than private insurance plans, thus making administrative costs smaller as a percentage of total costs. This creates the appearance that Medicare is a model of administrative efficiency. What Jon Alter sees as a “miracle” is really just a statistical sleight of hand.
