Expertise, experience, and excellence. Twenty years of patient involvement in health technology assessment at NICE: an evolving story.

From its inception in 1999, the National Institute for Health and Care Excellence (NICE) committed to including the expertise, experiences, and perspectives of lay people, patients and carers, and patient organizations in its health technology assessments (HTAs). This is our story of patient involvement in HTA: from early methods designed for use when assessing medicines, widening to address the different requirements of HTAs for interventional procedures, medical technologies, and diagnostic technologies. We also chart the evolution and development of all our patient involvement methods over the past 20 years through regular evaluation and by responding to external challenge. However, we know that processes and methods alone are not enough. Through case studies we demonstrate the value of patient involvement in HTA and highlight the unique perspectives and experiences that patients bring to HTA committees. Finally, we discuss the underpinning principles and commitments that have made NICE a world leader in delivering meaningful and legitimate patient involvement.