Patient reported outcome measures [PROMs] are standardized, validated questionnaires intended for completion by patients in order to measure their perceptions of their own health condition or its treatment without interpretation of the patient's response by a clinician or anyone else. Mayo Clinic Score [MCS] or Crohn's Disease Activity Index [CDAI], most frequently used as end points in conventional clinical trials, are composite instruments that are not fully objective nor capture the impact of disease from the patient's perspective. They are difficult to apply to routine clinical practice because they are complex and time consuming. The European Medicines Agency and Food and Drug Administration are re-evaluating composite indices in clinical trials and product development guidelines. The ultimate goal is to support labelling claims to improve safety and effectiveness of medical products through PROMs allied to an objective measure of inflammation, as happens informally in clinical practice. PROMs, developed and validated according to rigorous criteria, are set to become a co-primary end point for clinical trials of therapy, together with objective measure[s] of inflammation. This will affect future trials' design and their results. To find a place in routine care, PROMs should be easy to use, acceptable to patients and healthcare teams, and able to demonstrate added value to normal practice, supporting decision-making at the level of individual patients. Ideally, the same PROMs should be used in clinical trials and practice, to avoid the current disconnect when interpreting the results of clinical trials and translating them into routine clinical practice.