Causality in medicine: Getting back to the Hill top

doi:10.1016/j.ypmed.2011.08.009

Preventive Medicine

Volume 53, Issues 4–5, October–November 2011, Pages 235-238

https://doi.org/10.1016/j.ypmed.2011.08.009 Get rights and content

Abstract

Evidence from randomized controlled trials (RCTs) is almost universally regarded as setting the “gold standard” for medical evidence. Claims that RCTs carry special epistemic weight are often based on the notion that evidence from randomized studies, and only such evidence, can establish that any observed connection between treatment and outcome was caused by the treatment on trial. Any non‐randomized trial, on the contrary, inevitably leaves open the possibility that there is some underlying connection independent of receiving the treatment between outcome and one or more differentiating characteristics between those in the experimental and control groups; and hence inevitably leaves open the possibility that treatment and an observed better outcome were “merely correlated” rather than directly causally connected. Here I scrutinize this argument and point towards a more tenable and more modest position by recalling some of the forgotten insights of the RCT pioneer, Austin Bradford Hill.

Highlights

► The claim that RCTs carry special epistemic weight is analysed. ► Exaggerated claims on behalf of RCTs are identified. ► A more modest and more defensible position is sketched. ► This position is based on insights articulated long ago by Austin Bradford Hill.

Section snippets

Conflict of interest statement

I declare that there are no conflicts of interest relevant to this article.

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Cited by (17)

Clinical recommendations: The role of mechanisms in the GRADE framework
2022, Studies in History and Philosophy of Science
Citation Excerpt :
While RCTs certainly have epistemic and scientific values, they should not be considered flawless. See Borgerson (2016), Worrall (2007), (Worrall, 2020), (Worrall, 2011), Black (1996) and Cartwright (2013) for detailed descriptions of the limitations of RCTs. This paper takes the position that the incremental evidence gained by RCTs is perhaps overvalued in the GRADE framework.
The Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework has become one of the most influential frameworks for assessing quality of research and developing clinical recommendations. The GRADE framework has been presented as an evolution in the Evidence-Based Medicine (EBM) movement. Both GRADE and EBM emphasize effect estimates derived from population-level clinical trials and, as a consequence, devalue the role of mechanisms as the basis for clinical decisions. Although mechanisms do not hold the epistemic privilege of rigorous clinical trials in EBM reasoning, this paper will argue that mechanisms appear to be important in the use and application of GRADE, as described in the literature. The seemingly necessary role of mechanisms in the development of clinical recommendations has, so far, received little attention and is not explicitly featured in the literature describing GRADE. The analysis of the GRADE framework presented in this paper reveals an apparent tension between EBM's willingness to downplay mechanisms and what seems their inevitable use in GRADE. In this paper, we take the position that if mechanistic reasoning is inevitable in the use of GRADE, then the instructional literature on the framework would benefit from more explicit discussion of how to consider and integrate mechanisms.
Standards of evidence and causality in regulatory science: Risk and benefit assessment
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In other words, the appraisal of the evidence in favor of, or against, the existence of a causal connection would not depend on professional judgment. Recurring to RCTs is justified precisely for being a source of (supposedly) objective and neutral proof for the existence of causal connections, thereby substituting for expert judgment (Worrall, 2011). In fact, one of the explicit aims of the application of this first stance to regulation, particularly in EBM, is to eliminate the need for expert consensus conferences, where the aim is to assess the available evidence about the efficacy of particular medical treatments (Solomon, 2011).
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Establishing a causal link between social relationships and health using the Bradford Hill Guidelines
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While critically appraising the Bradford Hill Guidelines is valuable, it is beyond the scope of this paper to do so. And in defence of their use, the Guidelines are widely recognised as being both useful and influential (Chalmers, 2003; Doll, 1992; Hardy & Magnello, 2002; Horton, 2000; Phillips & Goodman, 2004; Wilkinson, 1997) and seen to reflect pragmatic or ‘common sense’ philosophical principles (Worrall, 2011). Another potential problem is that the Bradford Hill Guidelines were designed for clinical settings.
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View full text

Causality in medicine: Getting back to the Hill top

Abstract

Highlights

Section snippets

Conflict of interest statement

Nature's Capacities and their Measurement

The environment and disease: association or causation?

Proc Roy Soc Med

Reflections on the controlled trial

Ann. Rheum. Dis.

Principles of Medical Statistics

Effects of remote, retroactive, intercessory prayer on outcomes in patients with bloodstream infection

BMJ