Communicating risk is about numbers. If you think of any serious disease, the potential to reduce risk by 50% sounds fantastic. If the incidence is 2/10 and you reduce the risk by 50% you save one life in 10. If the incidence is 2/100 you save one life in 100. If the incidence is 2/1000 you save one life in 1000. So, are decisions on screening simply about dealing with relative risk reduction, absolute risk reduction, and the numbers needed to treat? Not quite. When you add in all the other epidemiological factors associated with screening it becomes very complicated. No wonder experts disagree and the public becomes confused.

At a workshop at the WONCA Europe meeting, we were asked to analyse two information leaflets on breast screening, one from the UK and one from the Nordic Cochrane centre, to help women decide. There were five groups and, in our group of 12 women and 7 men, there were probably only a handful over 40 years old. (Breast screening opinion is so polarised and highly sensitive, I am certain to upset someone. So, lets blame everything on the group.)

Our group, in a SWOT analysis of the leaflets, recognised and applauded efforts to make the language understandable and address the questions that patients might ask, together with efforts to address false positives and false negative. On the other hand, my colleagues thought there was too much information and that it would be very difficult to decide what was important. One view, which was elegantly reported by another group (you can see I am distancing myself even further…) was that the UK made a decision on screening, used evidence to justify the decision, and then wrote the leaflet. The Nordic centre looked at the evidence, made the decision, and then wrote the leaflet.

Its not that simple, however, in general practice (our group felt). Women tend to say—I don’t want to know about the numbers, I just want to know if I have cancer or not. And, having read the leaflet, even the most informed often ask—“and what do you think doctor.” As one of our group said “not as a GP but as a woman” she would like some direction or advice from a professional.  We also listed some of the many other social and cultural issues which include: How do doctors and patients feel about  “tempting fate”—we know that if we always err on the side of safety we may cause harm. Others believe that if there is technology available, why not use it. It is difficult, therefore, to argue in favour of what seems like doing nothing. It is also difficult to have shared decision making when doctors and patients are uncertain about the evidence—and even the leaflets make people feel insecure. There are socio cultural factors—how people value individual decision making versus the common good. In many countries there is a sense of citizen duty and social responsibility generating a feeling that if the government puts it in place, we ought to take it up.

What we need is independent professional advice. But, as editors know from seeking expert opinion for peer review, virtually everyone seems to have taken a position. Even if you try to be non committal, someone will attack you from one side or the other. So, my final answer is that……… I still don’t know.

Domhnall MacAuley is primary care editor, BMJ