“What if everybody did that?”

Many a parent has used this phrase when they’re trying to teach their offspring good manners, like not dropping litter in the park. What they may not realise is that they’re using an established economic concept – the so-called tragedy of the commons. This describes what can happen to a common resource – like the park, or common grazing land – when its users, if they only care for their own self-interest, act in such a way that ultimately it is spoiled (full of litter) or depleted (grazed bare) through their collective action.

The examples are all around us. An individual car on the road has no effect, but if everyone travels at the same time, we get long traffic jams. The carbon emissions of one household are insignificant, but put them all together and we get climate change. There are, however, less obvious instances; one of these is the use of antibiotics.

As most of us know, antibiotics are a class of drug used to treat patients with bacterial infections like otitis, meningitis or pneumonia, or to prevent people contracting them (e.g. patients prior to surgery, with HIV or during chemotherapy when their immune system is weakened). Since their discovery over 100 years ago, antibiotics have transformed medicine and prevented millions of premature deaths.

However, there is a looming problem with these medicines. The bacteria they combat so effectively are subject to the same ongoing natural process of mutation as the rest of the organic world; the bacteria that are killed cannot reproduce, and every so often, one of the organisms mutates in such a way that it resists the antibiotics and survives. When large numbers of these resistant bacteria start floating around and reproducing, we are in trouble.

Unfortunately, this is precisely what is happening; an increasing number of strains of bacteria are now resistant. One of the reasons for this is that antibiotics are sometimes prescribed when they should not be. A 2018 study by Public Health England estimated that 8.8-21.3% of prescriptions of antibiotics were inappropriate (depending on the strictness of the criteria).

It’s our behaviour

Unsurprisingly, over prescription of antibiotics is largely a matter of behaviour. Many patients see antibiotics as the ‘full-strength’ remedy for their ailments, and often do not know that they have no effect on viral conditions (like the common cold). As a result, they go to the doctor expecting (and even demanding) a course of antibiotics for a cough or a runny nose.

Of course, doctors could refuse. They could choose to advise their patients to take some paracetamol for the symptoms, stay in bed for a few days, keep hydrated and take it easy – in most cases, patients will recover without any medication.

But not always. A viral infection can compromise a patient’s immune system, and open the door for more serious bacterial infections. Physicians must consider this risk, and preventively prescribing antibiotics is one way of managing it. Even if there is no particular medical risk, patients will put pressure on their doctor; they have an important meeting at work, for example, or their child has an important test coming up.

Chris van Tulleken, a doctor convinced something needs to be done to change Britain’s over prescription habit, found this out first-hand when making a BBC documentary. He temporarily joined a doctors’ surgery with one of the highest prescription rate of antibiotics in its area and took over from one of its General Practitioners. Yet, despite his cheerful good intentions, he found it almost impossible to resist both the medical logic and the patients’ arguments, and in many cases prescribed antibiotics after all. It’s tough being the doc that says ‘no’.

This is a great example of a common behavioural barrier: the intention-action gap. There is a need for change at the macro level of a whole population, but ultimately the change needs to happen at the micro level of the individual. And that is hard.

Two powerful levers

So what can be done? Most doctors are well aware of the societal risk of over prescription, but when confronted with an actual patient, other concerns loom more prominently and influence their choice.

Social proof (i.e. raising awareness of what others do) is one possible strategy. In the documentary, van Tulleken showed his colleagues that 80% of the practices in the same area are prescribing fewer antibiotics. The Behavioural Insights Team, the group of behavioural scientists set up by the UK government in 2010, conducted a study with over 1,500 similar practices (with prescribing rate in the top-20%) to investigate how effective such an approach might be. They found that sending them a single letter explaining that 80% of the practices prescribe fewer antibiotics per head led to a 3.3% reduction in antibiotics use over a period of six months.

In another paper, a team from the University of Leicester identifies reputation-based incentives as a strong supporting instrument for social proof interventions. Practitioners that adopt a more conservative prescribing approach, could be rewarded and praised, and those who exhibit inappropriate behaviour could be sanctioned according to the scale and the frequency with which this happens.

Interestingly, both social proof and reputation were found to be effective in another health-related intervention. The workers in a Guatemalan food processing facility were not washing their hands for long enough before entering the plant. On average, about 25% of workers had more than the safe limit of germs on their hands (it was more than 40% in night shifts). Over a period of two weeks, workers were given a stamp on their hands, which they could only remove by thoroughly washing.

This provided not only a visible sign of how many of their colleagues washed properly, but it also had a reputational effect; anyone who still had a stamp on their hand was someone who hadn’t bothered, and who was potentially putting lives at risk. Even after the stamps were removed, the percentage of workers with ‘dirty’ hands fell by nearly two-thirds on average. (In the night shift, the drop was even higher at about three-quarters.)

The social proof approach is now being trialled in Greater Manchester. Family doctors will be able to compare their prescription behaviour with the national average through a dedicated dashboard, which will be rolled out nationally in the UK later.

Social proof and reputation are powerful levers for changing behaviour and habits. Unless we deliberately want to stand out, we prefer to do as others do, and we are quite protective of our reputation. Let us hope they can help us use antibiotics more responsibly.