A lady of pensionable age recently explained to me why she was a convert to handheld computer games. Playing them, she said, was cerebrally invigorating and fun. So much so, in fact, that she felt sure computer games could rewind her mental state to a more youthful age. She also disclosed that “him at home” couldn’t hope to provide a similar level of entertainment. I was about to start preaching about how “real” social interaction, rather than computer games, is known to be a crucial factor in healthy ageing – but no. She now felt five years younger.

The trend for putting ages on our faculties and organs is a curious one. I can see the appeal, but I find it hard to see how complex expressions of health risk can be satisfactorily compressed into a simple number.

Take, for example, working out cardiovascular risk. Using known risk factors such as family history, ethnicity, smoking, blood pressure and cholesterol, charts can plot where one’s future risk lies. However, a lot depends on which chart you choose. Doctors commonly use those from the “Joint British Societies” (British Cardiac and Hypertension Societies, and British Hyperlipidaemia and Diabetic Associations). Other calculators, such as “Assign” in Scotland, have been developed for this specific geographical area, and employ information from postcodes in addition to basic clinical data.

But when results from these charts express risk in percentage terms, does it provide any practical insight? Knowing that I have an 8 per cent risk of a heart attack in the next 10 years would be more useful if I knew whether it were above or below average, and if it could be changed, and by how much. We all carry some risk, some of which is modifiable, and some of which is not. Trying to compress all this information into an average GP consultation is hard.

Flora margarine is one of many appearing to offer quick answers. An e-mail from manufacturer Unilever landed in my inbox asking: “New heart age tool: did you know your heart could be a different age from you?” The tool calculated “heart age” via the usual lifestyle factors. Predictably, if you had an “older” heart age, it recommended you use Flora margarine. Until we have decent trials to examine the end-points of heart attack and stroke in relation to margarine, I will continue to buy butter.

But perhaps I shouldn’t be too cynical about this topic. A paper published in the BMJ last year showed that more than double the number of smokers were motivated to give up when told their “lung age”, compared with those who weren’t. This was worthwhile because a constructive benefit was offered. Can we say the same of handheld computers or margarine? I fear not.

Margaret McCartney is a GP in Glasgow
margaret.mccartney@ft.com

For lively discussion of the latest medical issues go to FT’s Healthblog