What does it mean to say a treatment “works”?

Sometimes when I’m in practice I may give an opinion on how well someone has improved in terms of the symptoms that they originally consulted me for. However, I am acutely aware, and often remark, that my opinion doesn’t really count for much: it’s the patient’s opinion that is most important. I could be delighted with their supposed ‘improvement’, but if they don’t feel any better or better off, then the desired end result has simply not been achieved.

The first time it ever occurred to me that there could be a disconnect between the opinions of doctors and their patients was while I was at medical school. I was in a pharmacology lecture, though I forget the precise topic. In the lecture, the presenter raised the issue of differences in the judgement regarding whether a treatment has been successful or not. He used as an example the hypothetical situation of a man being treated for high blood pressure with beta-blockers. The man had no symptoms from his condition (as is often the case with high blood pressure). Now imagine the beta-blocker works to reduce blood pressure. That would generally be regarded as a ‘result’ by most doctors. But imagine now that the patient has been made impotent by the drug. So, on the one hand, the doctor may view the treatment as a success, but to his or her patient, there is reason to view it as a dismal failure. This story still serves to remind me of the importance of judging the effectiveness of treatment by the patient’s needs (not my own).

Today’s British Medical Journal contains an interesting piece from Professor Nicholas Christakis, a doctor and professor of medical sociology based in Boston, USA. In it, he explores the potential differences in doctors’ and patients’ opinions on whether or not a treatment ‘works’. He cites a number of examples, including the effectiveness of sildenafil (Viagra) for the treatment of impotence. Trials may have shown sildenafil to be more effective than a placebo in restoring sexual function, but at a dose of 25 mg still only 28 per cent of men treated find it effective (as defined as success when sexual intercourse is attempted at least 60 per cent of the time). In other words, as Professor Christakis points out, at this dose, sildenafil does NOT work 72 per cent of the time. I’d say that most patients would not view this as a resounding success.

Another example cited by Professor Christakis concerns atorvastatin (discussed here last week) and the so-called ASCOT trial in which treatment with drug was found to reduce the risk of heart attack from 3 per cent (in those taking placebo) to 1.9 percent. The relative reduction in risk looks impressive, but because the numbers are small, the actual reduction in risk really very small indeed. Also, in my piece last week, I cite a review of 8 studies on atorvastatin which show that for one person to avoid having a cardiovascular event over a 5-year period, 67 people would have to be treated. That means, over a period of 5 years, the treatment is unsuccessful 98.5 per cent of the time.

Professor Christakis actually uses the ASCOT study data to make another point, about the effectiveness of placebo. Because, as he points out, 3 per cent of people taking placebo had heart attacks, then the placebo ‘worked’ 97 per cent of the time.

With regard to the effectiveness of drugs, Professor Christakis writes, Countless drugs that have been shown in randomised controlled trials to be effective work in only a minority of patients. Imagine that a drug worked 20% of the time in a trial, compared with 5-10% for a placebo. This is the case for drugs ranging from antihypertensives to minoxidil to cancer chemotherapy. Such a difference in a trial corresponds to an enormous effect size. However, most patients taking such drugs would not benefit”they would hardly think that the drugs “worked.”

If you buy a toaster you expect it to be able to toast bread every time it is used. If it does not, you say it does not work and return or discard it. You do not take solace from the claim that, in fact, 30% of the time in the manufacturer’s laboratory the toaster did a better job in browning bread than sunshine alone. He calls the habit of doctors saying a drug ‘works’ because it outperforms placebo in clinical trials as a naïve oversimplification.

Professor Christakis calls for careful appraisal of the effectiveness of drugs in the future, including the taking into account of data which tells us about variations in treatment responses that may relate to factors such as age and the extent of the condition being treated. He also encourages more careful appraisal of the effect a drug is having in an individual patient. He closes be writing, Just because drugs work in trials does not mean they will work in our patients. In fact, we can often expect that they will not work at all.

My opinion is that the pharmaceutical industry, often aided and abetted by medical practitioners, consistently overstates the value of the products it sells. Taking a more patient-focused and individualised approach, as Professor Christakis advocates, makes good sense, I think. And his piece has also highlighted the just how ineffective some medical treatments have been proven to be.

References:

Christakis NA. Does this work for you? BMJ 2008;337:a2281

One Response to What does it mean to say a treatment “works”?

  1. Methuselah 1 November 2008 at 12:31 am #

    Admirable restraint, Dr B, in your final paragraph. No doubt you would agree that the pharmaceutical industry is no more interested in an individualised approch to treatment than industrialised farmers are interested in high quality nutrition. For both it’s all about volume and margin – pile ‘em high, sell ‘em cheap. Their business model is too far removed from what is best for the consumer, so rather than change what they do when this becomes clear they are forced into methods that distort the truth.

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