Mechanistic reasoning and informed consent

Evidence-based medicine (EBM) proponents have argued that mechanistic evidence concerning medical treatments should be considered secondary to evidence derived from randomized controlled trials (RCTs). One common criticism of RCTs is that they often do not yield results that are generalizable to clinical practice, and that for clinical practice application, mechanistic evidence is needed. However, proponents of EBM have argued that mechanistic reasoning is often unreliable and thus not very useful. Here we suggest an important role of mechanistic explanation that has been left out of this discussion entirely, namely, its importance in a patient's decision of whether or not to take certain drugs. We argue that in certain cases, knowing how a treatment works is just as important for the patient as knowing whether it does. In this paper, we explore how and why giving patients mechanistic information can be an important factor in obtaining informed consent for medical treatment, focusing on the example case of hormonal contraceptives.