Informed consent
Authors: M. Baum, I G Kestin, S E Josse, D. H Brewster, M. R S Bain, J. W T Chalmers, A. Gould, J. A Dewar, W D. George, J. Nottingham, A. J Winter, D. Mullis, K. W Radcliffe, D T Wilcox, F Wilcock, L Spitz, A Pierro
Journal: BMJ (1998)

Editor—Smith’s editorial recognises the complexity of the issue of informed consent and states that the BMJ is prepared to relax its absolutism.1 At the risk of being misunderstood I would like to attempt to construct a decision theory model based on certain explicit assumptions that may allow us to compute numerical values better to inform the debate. At the outset I accept the ethical principle of non-exploitation so beautifully described by Mary Warnock2; I also accept the importance of consumers’ involvement (I was the founding father of the consumers’ advisory group for clinical trials chaired by Mrs Hazel Thornton).

Let us anticipate 150 000 deaths from breast cancer in this country over the next 10 years and let us make the conservative assumption that we already possess a novel therapeutic adjuvant that in absolute terms would reduce the risk of death by 6% over this period—in other words, save 9000 lives.

Next let us assume that the UK Coordinating Committee for Cancer Research has approved three different clinical trials evaluating three promising new agents, any one of which might produce this desired 6% absolute reduction in mortality, which is equivalent to a relative risk reduction of about 25% for patients with an average prognosis. Each trial would need to recruit about 2000 patients to have adequate statistical power to detect this order of relative risk reduction. Let us now suggest that trial A will show no difference between best standard treatment and the new treatment. Trial B will show that the new treatment will produce the desired benefit, and trial C will show that the new treatment is worse by the same order of magnitude. In aggregate 6000 women will have been recruited to these three trials. Altogether 120 will be better off than if they had had best standard treatment, and 120 will be worse off than if they had best standard treatment.

If we have an efficient clinical trials organisation then on past experience we might expect at the best to recruit 1000 patients a year, so whether the trials run in parallel or in sequence the total recruitment time will take six years. So far I have based my assumptions on the experience of using conventional informed consent procedures. Now, for example, let us perturb the model by prerandomising the patients within the trial, seeking consent for the treatment on offer while not discussing the issues of the random allocation of treatment; it is pure speculation as to what extent this will speed up recruitment into the trials. I would guess that a conservative estimate would be doubling the rate of recruitment so that the total sample will have accrued in three years rather than six years. Let us then assume that the results of the trials are implemented rapidly within the country once the results are available. We can then calculate the price of autonomy. A treatment that produces an absolute reduction of 6% a year would save 900 lives a year; the price of autonomy is the cost of 2700 lives lost.

It is not the role of someone like myself or the medical profession as a whole to judge these issues, but we could go back to true representatives of the lay public by way of postal surveys or focus groups to discover what price the public puts on the ethical imperative of self determination.