Posts Tagged ‘ Risk ’

First, Do No Harm


Primum non nocere

A while ago I was accused of advocating that doctors should break the Hippocratic oath. That the cardinal rule of “First, do no harm” should be ignored. Setting aside that this phrase does not appear in the Hippocratic oath, what do we mean by harm in the context of medicine?

I was reminded of this by a post on Science Based Medicine by David Gorski in which he muses over the measure of patient satisfaction as a proxy for how well hospitals meet their obligations with regard to patient care. To kick it off the good doctor notes that many interventions used by modern medicine cause harm, often direct harm.

Does this mean that doctors are throwing out their obligation not to harm patients? No, because we recognise that the concept of harm in this case includes those harms that would occur were we to withhold treatment as well as recognising that the total harm is reliant on the amount of benefit obtained by the patient.

The accusation against me was in the context of my arguing against the claims of anti-vaccinationists that vaccines do more harm than good. I don’t want to rehash that argument here but I do want to dwell a bit on our concept of harm and how it applies in the medical arena.

One of the themes that return to over and over again on this blog is that of risk vs benefit. The amount of harm or risk can only be appropriately assessed in light of the benefit accrued. As pointed out by doctor Gorski there are many procedures that hurt, they hurt a lot. Should a doctor refuse to perform them then? Even if they could save a patient’s life?

Of course not.

It is plainly ridiculous to assert that short term harm out weighs long term benefit, it might but that calculation has to be made in each case. In many cases the benefit will be clear, in others less so. If a patient undergoes a painful procedure that is relatively short lived and then makes a full recovery then the choice is fairly simple. If the recovery is likely to be only partial and the patient’s quality of life is ever after severely reduced then we may weigh up the benefits of that treatment differently.

What then of treatments that are good for most but may harm a few? These are the tricky cases and it depends on a few variables. One is can we identify the persons that will be harmed,  second, how much harm are they likely to suffer and what percentage of the treatment population do they make up? Finally what total benefit will accrue to the population if treatment is green lit?

I listed these variables in the order of importance I estimate they have. If we can identify prospectively harmed persons then they may be removed from the treatment group, harm avoided. If this information is unavailable then we may move to the next criterion: how much harm will they suffer? If this is likely to be relatively mild then all to the good. If the harm is considerably more serious then we may stop the treatment altogether in order to avoid these instances. The last two variables may switch in order depending on the situation or individual values.

Should a vital treatment be withheld from the general population if a very small percentage with be greatly harmed by it? Frankly I don’t know. Help – is there a Medical Ethicist in the house?

Often I’ll find that the people who oppose modern medicine will emphasise the risks of medicine while over-hyping the benefits of alternative medicine. The claims that iatrogenic (caused by medical treatment) harms are enormous abound. This point of view seems completely ignore the benefits received by individuals and society by medicine in it’s current form*.

This seems perverse to me, the idea appears to be that any risk is unacceptable – a completely untenable position to my mind – every action carries risk. I take my life in my hands every time I drive to work, but the risks a relatively low and the benefits are more important to me – and the majority of other drivers I suspect. To argue that we should abstain from automotive transport until it is completely safe misses the point entirely. As does decrying the risks of the majority of medical science in the face of the undoubted benefit received.

To conclude this ramble, harm or risk is part of the human condition. Arguably the complete removal of risk is not only impossible but not even desirable**. We have to live with risk and harm, the key is to ensure we balance these against the good that comes from acting in the world to oppose even greater harms.

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*This is quite an extreme view and I would hasten to add that I don’t think the majority of alternative medicine users (however you may break that group down) would subscribe to it, but it exists.

** Depending on how this might be achieved. Possibly we could make ourselves impervious to harm rather than removing everything that might harm us.

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The Risky Business of Hunger


ResearchBlogging.org

We like to think of ourselves as rational actors when it comes to making decisions, we take in information, process it and choose the path that we think will lead to a desirable outcome (if we aren’t deep-seated masochists I suppose). Regular readers of this blog and others that espouse a sceptical viewpoint will know that this isn’t really the case. We are influenced by a large number of factors from implicit biases, to environmental factors, and errors of thinking. The hope is that if we are aware of these factors we can go some way toward mitigating their effects and making choices that are both rational and lead to improving our lives.

Well, here’s another one for you. You may have guessed by the title of this post that it involves food and risk taking behaviour. A paper published last month in PLoS ONE out of the University College London looked at how hunger and food intake affected choices that had a monetary reward. The actual experimental design ran something like this, subjects fasted for 14 hours they then performed tasks that in effect were an idealised lottery, the tasks were performed before, directly after and an hour after a standardised meal. Over this time the subjects also had blood samples taken to measure hormones that correlate with hunger and energy reserves.

The task subjects had to perform consisted of choosing one of a pair of “lotteries” where there was a 25% chance of receiving one of four monetary amounts. Each pairing was designed so that there was always a difference in risk between the two  (see the picture it’s hard to explain).

Paired Lottery doi:10.1371/journal.pone.0011090.g002

How the subjects performed on the tasks was measured to determine the amount of risk aversion. In other words, humans have a tendency to normally prefer less risky choices. The effect of of hunger and especially immediate satiation (right after eating the meal) is to decrease this risk aversion and to make the subjects more risk neutral.

This way of referring to the subject matter is a little counter intuitive and can take a bit of getting used to, the bottom line is that the researchers looked for the point at which the subjects were equally likely to choose the “safe” bet which promised an certain average reward, and a “risky” bet that may lead to a higher average pay off but a lower chance of receiving it. Thus risk aversion has been reduced. By varying the reward amounts the researchers can measure the degree of risk aversion in each subject as the trial proceeds.

Actually the correlation is more complex than I would have thought, not only is the fact that calories are received taken into account but also the amount of calories. It seems that the size of the meal (in terms of calorific intake) is assessed to determine if it meets the rate of food intake required to meet baseline energy requirements. If it does risk aversion is increased (less risky behaviour) if not the risk aversion is decreased.

In hormonal terms this meant that a greater drop in the hormone associated with hunger was correlated with greater risk aversion but a smaller drop meant an increase in risk taking behaviour. The study authors also note that the adiposity of an individual (eg higher BMI) correlated with the size of the hormonal decrease after eating with higher BMI subjects experiencing a smaller drop and a corresponding greater increase in risk taking behaviour.

In effect we not only look at the reward in terms of the gain we will receive compared to our external resources (cash in the bank, say) but also in relation to our internal resources (metabolic requirements for example). This makes sense if we consider that for most of our history true advantage was not measured in abstract accumulation of “wealth” which we would recognise today but in available energy, including that within our bodies. That’s just a speculation of course, I’m no expert in this area.

What is the take home message of this research then? Well first off we should be careful to realise that risk taking behaviour is not limited to single domains in our lives. If you take away from this that only financial decisions are affected then that is too narrow an interpretation. In the final analysis though, no matter our eating habits or body size, we should endeavour to think over important decisions carefully and be aware of the changeable nature of our biology and it’s effects on our thinking.

Symmonds M, Emmanuel JJ, Drew ME, Batterham RL, & Dolan RJ (2010). Metabolic state alters economic decision making under risk in humans. PloS one, 5 (6) PMID: 20585383

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