The evaluation of treatments and care processes is systematically considered under the prism of Evidence Based Medicine and the randomized controlled trial as an inescapable model. There is in this model, a great absentee, the patient and his experience. From our perspective, prior identification of the relevant NPI efficacy indicators, in support of the structured and rigorous in-depth exploration of the patient’s experience in care, is essential. It is in this perspective that qualitative research finds its place. It is a question of proposing a complete methodology that structures the whole research process and makes it possible to position the patient’s experience as the irreducible space of care.