The evidence that evidence-based medicine omits

• Published in: Preventive medicine Vol. 57; no. 6; pp. 745 - 747
• Main Authors: Clarke, Brendan, Gillies, Donald, Illari, Phyllis, Russo, Federica, Williamson, Jon
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.12.2013; Elsevier
• Subjects: Biological and medical sciences; Causality; Confounding Factors (Epidemiology); Evidence; Evidence based medicine; Evidence hierarchy; Evidence-Based Medicine - methods; Evidence-Based Medicine - standards; Humans; Internal Medicine; Mechanism; Medical sciences; Methods; Miscellaneous; Philosophy; Prevention and actions; Public health. Hygiene; Public health. Hygiene-occupational medicine; Randomized Controlled Trials as Topic - standards; RCT; Reproducibility of Results; RCT; Evidence; Evidence-based medicine; Methods; Philosophy; Mechanism; Evidence hierarchy; Methodology; Evidence-based practice; Method; Hierarchy; Randomization; Clinical trial
• ISSN: 0091-7435; 1096-0260; 1096-0260
• DOI: 10.1016/j.ypmed.2012.10.020

According to current hierarchies of evidence for EBM, evidence of correlation (e.g., from RCTs) is always more important than evidence of mechanisms when evaluating and establishing causal claims. We argue that evidence of mechanisms needs to be treated alongside evidence of correlation. This is for three reasons. First, correlation is always a fallible indicator of causation, subject in particular to the problem of confounding; evidence of mechanisms can in some cases be more important than evidence of correlation when assessing a causal claim. Second, evidence of mechanisms is often required in order to obtain evidence of correlation (for example, in order to set up and evaluate RCTs). Third, evidence of mechanisms is often required in order to generalise and apply causal claims. While the EBM movement has been enormously successful in making explicit and critically examining one aspect of our evidential practice, i.e., evidence of correlation, we wish to extend this line of work to make explicit and critically examine a second aspect of our evidential practices: evidence of mechanisms.