Safe and effective

Health interventions can’t stake such a claim: So what should we say?

We have all been exposed to endless claims of the evidence that backs up the decisions, especially politically motivated ones. How often have you heard or read that you should do something because it is “safe and effective”?

Well, the mantra is epidemiological drivel: here’s why.

“Safe and effective”, although a seductive phrase, assumes or implies that whatever you are embarking on is 100% effective and 100% safe or near enough. It’s safe to cross the road means you’ll get to the other side. 

However, health interventions can’t stake such a claim. In epidemiology, we like comparative designs; we like comparing interventions, their benefits and drawbacks so we can apply a logic called induction. Induction was first expressed in its modern form by Francis Bacon, an English philosopher and statesman who advanced the scientific method.

Even better, comparative evidence that reports similar results over time can get close to statistical significance. This is not certainty (there is no such th…