Some illnesses are more expensive to treat than others. While most people accept this fact, they do not like the idea that healthcare might be rationed according to cost, and react angrily to suggestions that certain interventions might “cost too much”.

The relative cost-effectiveness of different treatments can be difficult to pin down. The National Institute for Clinical Excellence, for example, assessed drugs for the treatment of dementia and rejected them on the grounds of excessive expense – a decision criticised by those who believed the potential cost-saving on carers’ time was not being evaluated correctly. This kind of problem occurs in all sorts of medical treatments, where the discrepancy between research findings and real-life outcomes are hard to measure.

Take angina, which, until the 1960s, was treated with drugs. Next came coronary artery bypass grafting (CABG), developed to supply the heart muscle with blood when its own circulation failed, usually due to plaque formation (atheroma) in an artery.

More recently, a range of PCI (percutaneous coronary intervention) techniques has been developed. Instead of opening the chest, a catheter is run from the artery in the groin or arm up towards the heart. By using devices such as balloons, or by inserting stents, some impregnated with drugs, the narrowed artery can be opened so that the heart muscle is once again supplied with blood. There is huge enthusiasm for these techniques and they have been rapidly adopted in many hospitals.

Which is better – or more cost-effective? PCI is minimally invasive, faster to perform and allows quicker recovery. Bypass surgery, meanwhile, has been linked to a higher risk of stroke or cognitive impairment (probably because of mini-strokes during the operation). But it improves mortality rates for up to 10 years, whereas the advantages of PCI seem to disappear two to three years after the procedure.

There are other financial burdens associated with PCI. The stents, if drug-eluting, can cost several thousand pounds. One analysis of current data also estimates that while stents do reduce the rate of vascular complications, they have no overall effect on heart attack or death rates. Indeed, a Syntax study, recently published in the New England Journal of Medicine, found that people with severe coronary artery disease fared better after a bypass than after PCI. Other studies have produced similar results.

Keeping scores on cost-effectiveness can be a good way of helping patients to make choices about healthcare. The problem is that cost-effectiveness calculations often raise more questions than they can answer.

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

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