Understanding Risk


There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy. This quote from Hamlet has always stuck in my memory; it reminds me to be humble, especially in the face of the unknown. Uncertainty has always been anathema to most of us. We need explanations and we crave stability; anything falling short of those expectations leaves us feeling anxious. Suspicious. It’s why we have experts, after all.

The recent verdict of an Italian court that a group of scientists failed to adequately warn the citizens of L’Aquila of a deadly earthquake in 2009 is perhaps a case in point. That guilt could be assigned because the risk, although quantifiable, could not be accurately assimilated, means to me that it was meant as an indictment of Science and its methods. A vilification, really. That statistics are misunderstood is probably the explanation.

I don’t pretend to understand them myself, so I can see why things seem so mysterious. Saying there’s a 99% chance that something won’t happen this year, or this time, or in June, for example, means to most of us that it won’t happen. We’re willing to give weather forecasters some leeway, perhaps, but not experts that are supposed to help us avoid tragedy. After all, it’s their field; they’re supposed to know something about it…

Medicine is not exempt from this expectation either. Patients ask me what possible complications might happen with or after a particular operation -a simple question. I should know the answer. But the answer really depends on how it’s understood, doesn’t it? For example, if I state that there is a 1% chance, say, of needing a blood transfusion after a Caesarian section, that might be heard as “Really unlikely! You won’t need one unless things go very wrong.” But it could equally be heard as “Caesarian sections should not be undertaken lightly and things can go wrong.” Both are correct, and yet we hear what we need to hear. What we want to hear.

How unlikely should a risk be before it is not mentioned? Or should every risk be mentioned? Is it really helpful to tell a woman in labour with a baby in distress that there is a risk she could die during a Caesarian section, but that the baby could die if the surgery is not performed? Or that there is a -what?- small chance that she could end up with permanent paralysis if she has an epidural inserted to ease the pain of her labour? I agree that discussion of risks is important, of course, but I’m just wondering at what level it might become counter productive. Think of a map of a shoreline of a country. On a small scale it serves the purpose of indicating where the country lies in relation to its neighbours. A larger scale identifies harbours or perhaps small outcrops of land. At some stage as we increase the scale, however, it becomes unusable: boulders at the foot of trees growing at the edge appear, small indentations worn away by waves emerge; what appeared to be a smooth shoreline now seems to be a random squiggle of smaller and smaller indentations. They’re all part of the shoreline, of course, but the inclusion of more and more details obscures the original intent of the map.

I sympathize with the Italian scientists. Detailed description of the risks of each mode of delivery of a baby, for example, inevitably leads to closed loops. If I describe the possibility of maternal perineal injury from a vaginal birth (incontinence, painful scarring, infection -the list is interminable, depending on how minor the trauma)- I am then forced to describe the possible complications of the alternative: Caesarian Section. And depending on the level of seriousness of complications that is demanded, I am forced to admit that they are both dangerous procedures with unpredictable consequences. Now what? Select from the possible risks and consequences using the very statistics that were probably the source of the confusion in the first place?

I am and have always been in favour of full disclosure of risks and consequences. The equation of hazards, as it were, needs to be solved. And yet what is it that the patient is really asking? What were the citizens of L’Aquila asking? Translation is required: explanation in context. In the case of the patient asking whether or not to have an elective Caesarian, the answer may well be an exploration of why they needed to ask in the first place. Are they afraid of labour? Of pain? Of severe and irreparable injury?Addressing those issues is likely to be a more fruitful first step on the journey, than taking the one of playing with figures.

And in terms of the earthquake tragedy? How to negotiate that equation? I don’t know; I suppose it all comes down to meaningful, understandable and contextual communication. Perspective -both that of the public and the science. Respect.

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