INTRODUCTION: There is growing recognition that in order to remain sustainable, the UK's National Health Service must deliver the best patient outcomes within available resources. This focus on outcomes relative to cost is the basis of value-based healthcare (VBHC) and has led to interest in the recording of patient-reported outcome measures (PROMs) to measure patient perspectives on the impact of a health condition on their lives. Every health board in Wales is now required to collect PROMS as part of routine care. We will evaluate the VBHC programme implemented in a lead health board. The study aim is to understand what works about PROMs collection, for whom, in what contexts and why in a VBHC context. In addition, we will assess the social value of integrating PROMs collection into routine care.

METHODS AND ANALYSIS: A three-stage mixed-methods study comprising a realist evaluation integrated with social return on investment (SROI) analysis across four conditions; Parkinson's disease, epilepsy, heart failure and cataract surgery. Workstream 1: Development of logic models, informed by a scoping review, documentary analysis, patient and public involvement (PPI), staff and key stakeholder engagement. Workstream 2: Realist evaluation building on multiple data sources from stages 1 to 3 to test and refine the programme theories that arise from the logic model development. Workstream 3: SROI analysis using interview data with patients, staff and carers, stakeholder and PPI engagement, anonymised routinely collected data, and questionnaires to populate a model that will explore the social value generated by the implementation of PROMs. Findings across stages will be validated with key stakeholders.

ETHICS AND DISSEMINATION: The study is approved by Wales Research Ethics Committee #5 (22/WA/0044). Outcomes will be shared with key stakeholders, published in peer-reviewed journals and presented at national and international conferences.This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) licence, which permits others to distribute, remix, adapt, build on this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial.