It may seem perverse in a discussion of discovering cures in medicine to focus on the thalidomide case. Yet, as we shall see, the thalidomide case, though deeply tragic, is, at the same time, very instructive. It shows, among other things, that a cure cannot be said to have been discovered until it has been shown that it does not cause significant harm to the patient. Thus evaluating evidence for safety plays a crucial role in drug discovery, and, in the thalidomide case, consideration of evidence of mechanism was very important in assessing safety.
Month: June 2016
A core area of interest for EBM+ scholars is evidential pluralism. This is the thesis according to which to establish a causal claim (in medicine, but also elsewhere) we need multifarious evidence. More specifically, we need evidence that causes make a difference to their effects, and evidence of how causes produce effects. This way of combining different pieces of evidence should give causal claims better support (in accordance to the analogy of ‘reinforced concrete’, as discussed by Clarke et al.
One could think of evidential pluralism as a way of generating consensus on scientific claims. But what if we disagree? In this presentation, Federica Russo presents work in progress with Veli-Pekka Parkkinen and Christian Wallman. They examine the controversy generated by the ‘cholesterol hypothesis’: fatty diet causes heart disease. Through a detailed historical analysis of this case, they attempt a characterisation of scientific disagreement according to two main elements: where – in the scientific process – scientists disagree and why it is so. The broader aim of this study is to provide insightful conceptual tools to analyse present-day controversies.
Federica Russo is assistant professor at the University of Amsterdam and a member of the EBM+ consortium. Federica presented on ‘Evidence, causation and scientific disagreement‘ at the EBM+ workshop ‘New frontiers for evaluating evidence in medicine‘, which took place on 20 June at UCL London. Read and download Federica’ s talk here.
The EBM+ workshop ‘New frontiers for evaluating evidence in medicine‘, which took place on 20 June at UCL London, started off with Andy Fugard looking at talk of mechanisms in psychological therapy. Andy’s presentation is titled ‘What we talk about when we talk about mechanisms in psychological therapies’. You can read it or download it here.
I was particularly pleased to read the recent BMJ paper by Margaret McCartney et al, which discussed ways that EBM-based guidelines might be made to better serve the need of individual patients. I’ll urge you to read the whole thing (it’s not long at all), but here, I want to develop one of their themes a bit.
Their argument is that guidelines have become transformed into tramlines, or excessively inflexible rules determining the correct treatment for an individual.
They make other arguments too – such as that guidelines “exceed the limitations of the evidence for many people”. Although this raises an subsidiary point about the disparity of power between clinicians and patients, it gets us into epistemically difficult territory too – that guidelines, these paragons of objectivity and reliability – may end up as an expression of expert option rather than evidence. A startling factoid from this discussion – “Only 11% of American cardiology recommendations are based on high levels of evidence, with 48% based on the lowest level of evidence and expert opinion.“)
Back to the tramline argument: the thumbnail sketch here is that guidelines have been diverted from their original purpose of reducing variation in patient care (A Good Thing) to an authoritarian and bureaucratic imposition that threatens patient autonomy and clinical judgement (A Bad Thing). McCartney et al don’t present things in this cartoon-badman way, and it’s not a position that I would straightforwardly endorse, but there’s something to be said for taking a more subtle form of this transition seriously. For example, General Practitioners in the UK are assessed by a series of targets called the Quality and Outcomes Framework (or QOF, to its friends). While these guidelines are optional (i.e. GPs don’t need to enrol on the scheme),they are linked to financial incentives – dubbed ‘pay-for-performance’. It is therefore in the financial interest of GPs to fulfil as many of the QOF indicators as possible in as many of their patients as possible. The indicators themselves are not terribly controversial. For example, they say that GPs should measure and reduce cholesterol in people with heart disease:
The percentage of patients with coronary heart disease whose last measured total cholesterol (measured in the preceding 12 months) is 5 mmol/l or less.
Given the link between pay, and fulfilling this indicator, it’s not hard to paint the QOF as a tool that aims at compliance, rather than one that aims to make individuals healthier. As Richard Lehman recently blogged, the QOF doesn’t seem to make people live longer.
Note that this isn’t an argument against all one-size guidelines. Some of these (flu vaccination is the example cited by the authors) make sense both for individuals and for groups. But sometimes, the best option for an individual might not coincide with the best option for the group. ACE inhibitors work well to control high blood pressure, but cause severe cough in about 20% of patients that take them. For groups that are fond of the sound of their own voice (like, you know, university lecturers) this side-effect is particularly disabling, and an alternative antihypertensive drug might be a better option, even if they are fractionally less effective at reducing BP than an ACE inhibitor.
The point that I take from this paper is that combining patient preferences with clinical evidence is highly desirable, but complicated. The ACE-inhibitor example above appears dead simple, but developing tools to assist decision-making that really takes account of patient preference that is generally fit for purpose is much harder. How can clinical standards be maintained, with as little unwarranted variation in standards of care as possible, while accommodating individual patient needs, values, and preferences?
McCartney et al appear to agree with this. Their recommendations, at the end of the paper, as that “Patient decision aids should be published in tandem with guidelines, but better research is required into how to provide information about choices that is easily and quickly understood”.
Words by Brendan Clarke