Who We Are

EBM+ is a network of people seeking to improve the ways in which evidence-based medicine handles evidence of mechanisms. The organisers took part in a three-year, AHRC-funded research project, 'Evaluating Evidence in Medicine' (EEiM).


What is EBM?

Causal claims are crucial in medicine. Bugs, injuries and environmental factors cause disease and other symptoms; medicines, other treatments and public health policies alleviate or prevent such problems. Evidence-based medicine is a collection of methods for evaluating the evidence for and against causal claims like these. It provides grading systems and hierarchies of evidence, to help weigh up the evidence and to help decide whether there is sufficient evidence to establish a causal claim.


What is EBM good at?

EBM is good at weighing statistical evidence of associations. Statistical trials are used to test whether there is an association between the putative cause and effect. These trials vary in size and methodology, and EBM has developed ways of ranking these statistical studies.


What is EBM bad at?

EBM is error-prone for a number of reasons.  For example, blood pressure trials are typically administered on clean populations, whereas the treatment is usually given to people with multiple morbidities. Also, hardly any trials are done on pregnant women or for drugs with little financial promise. More generally, EBM does not account for the fallibility of randomised controlled trails (RCTs). One key reason why EBM is error prone is that it does not take evidence of mechanisms into account in a systematic way.


Why does EBM need improving?

Evidence of mechanisms plays an important role in establishing causal claims. Such evidence is often crucial when it comes to devising a statistical study; interpreting its results; deciding whether an association is causal, due to some other sort of connection, or a statistical blip; or applying the results of a study to a new population or a particular individual. High quality evidence of mechanisms can be produced by statistical studies, but it can also come from literature searches, one-off experiments, imaging, simulations etc. At the moment, EBM does not pay enough attention to mechanistic studies. Arguably, we need to take all relevant evidence into account, not just statistical evidence of associations.