Randomized controlled trials (or RCTs, for short) are, according to the paradigm initiated by evidence based medicine (or EBM, for short), the most accredited tool to establish whether drugs or treatments are effective, and to what extent. Surely, this is not stated in such explicit term, but it is quite easy to infer looking at the different versions of evidence hierarchies and of grade systems (for a discussion, see here). The logic behind RCTs is relatively simple, although it is the implementation being problematic in most cases. To know whether a treatment is effective we need to compare two groups of individuals, one that does take and the other that does not take the treatment. A crucial assumption behind RCTs is that individuals (at least in the trials) respond to the treatment in the same way. This is called ‘universal biological response’.

But what if individuals do not respond to treatments in the same way? This is precisely one of the questions behind gender medicine. Gender medicine thus points the finger to an important epistemological issue: to what extent can we safely make the assumption about universal biological response? And even more importantly, should (gender) medicine strive to understand (and accommodate) differences, rather than flatten out diversity?

The question isn’t innocent and in fact sparks a whole battery of new questions. For instance: if relevant difference concerns gender, do they also concern ethnicity? What are the relevant biological, social, psychological factors that play a role in different responses to a same treatment? And mostly, how do we know?

These questions are broadly epistemological in that they concern how we come to know (or fail to have knowledge of) about similar or different responses to treatments. Taking these questions seriously has important repercussions, for instance, on our medical methodology, and on the concept of individual, well being, or efficacy.