This study comprehensively reviewed reports on patient and public involvement and engagement (PPIE) in health technology assessment (HTA) overseas and identified the status and possible future measures, of PPIE in Japanese HTA.

The series of reviews targeted systematic reviews (SR#1), references in SR#1 (SR#2), and new articles after SR#1 (SR#3). The MEDLINE and Embase databases were searched through August 2024 using the terms “patient involvement/engagement,” “patient participation,” “community participation,” “public involvement/engagement,” and “health technology assessment.” The implementation details were extracted from information published on the websites of the HTA agencies.

Three review articles in SR#1, 12 references in SR#2, and 10 articles in SR#3 were selected. The opportunities for countries, including Japan, to participate in discussions on the HTA process did not differ significantly; however, information on PPIE in Japan was scarce and did not indicate their purpose and value.

Collected articles indicated that the value of PPIE in HTA includes relevance, equity, fairness, legitimacy, and capacity building. The participation of patient and public representatives in Japanese discussions since 2005 appeared to be very limited to consider PPIE in HTA. In countries that implement PPIE in HTA, the value of PPIE is explicit: the process guidelines are specific and provide an appropriate environment for input that includes education, training, and feedback. Future reforms of the Japanese system will require discussions on PPIE purpose and value, implementation, and creating an environment in which a diverse range of patients and the public can easily express their views.