Over the last two decades, social sciences have renewed their interest in patient organizations (POs) and activist groups in the domain of health and medicine. One of the main focuses of research about POs has been their engagement in the production and use of knowledge. Firstly, research has identified how certain POs actively intervene in “war on disease”, collaborating and critically engaging with biomedical researchers in what Steven Epstein (1995) has labeled “treatment activism”. These “treatment activists” learn science and progressively turn into credible interlocutors of scientists. Secondly, studies have documented how competencies and prerogatives are re-distributed between credentialed experts and lay members as POs collect, formalize and circulate patients’ experience, becoming what I suggest to call “experts of experience”. Thanks to this experiential knowledge, POs legitimately claim to take part in the shaping of health care services and health research policies. Thirdly, knowledge, and the collective negotiation about what counts as such, is seen to play a significant role in managing accountability and regulation processes in health care. POs are increasingly involved in such processes, contributing to and evaluating the “evidence-base” of collective decision-making (Moreira, 2011).

This expanding set of knowledge-related activities deployed by POs can be encapsulated by the concept of “evidence-based activism” (EBA). “Evidence-based activism” entails that the core of POs’ expertise is producing, staging and weighting different species of evidence within a process that involves a political appraisal of the issues at stake, of the competencies and prerogatives of the various participants, and of their own matters of concern. “Evidence-based activism” thus identifies a shift in POs’ mode of activism, from a situation where knowledge is seen as means to achieve the organization’s aims, to a configuration of action that reflexively engages with knowledge itself. In this communication, I will elaborate on this concept and provide illustrations drawn on a European research project called EPOKS that my colleague Madeleine Akrich and I are currently coordinating. This project involves comparative research between POs active in four condition areas (rare diseases, Alzheimer’s disease, ADHD – Attention Deficit Hyperactivity Disorder, childbirth practices) in four European countries (France, UK, Portugal, Ireland).