This paper aims to describe the development of a flowchart to guide the decisions of researchers in the Spanish Network for Health Technology Assessment of the National Health System (RedETS) regarding patient involvement (PI) in Health Technology Assessment (HTA). By doing so, it reflects on current methodological challenges in PI in the HTA field: how best to combine PI methods and what is the role of patient-based evidence.

A decisional flowchart for PI in HTA was developed between March and April 2019 following an iterative process, reviewed by the members of the PI Interest Group and other RedETS members and validated during an online deliberative meeting. The development of the flowchart was based on a previous methodological framework assessed in a pilot study.

The guidelines on how to involve patients in HTA in the RedETS were graphically represented in a flowchart. PI must be included in all HTA reports, except those that assess technologies with no relevant impact on patients’ experiences, values, and preferences. Patient organizations or expert patients related to the topic of the HTA report must be identified and invited. These patients can participate in protocol development, outcomes' identification, assessment process, and report review. When the technology assessed affects in a relevant way patient experiences, values, and preferences, patient-based evidence should be included through a systematic literature review or a primary study.

The decisional flowchart for PI in HTA contributes to the current methodological challenges by proposing a combination of direct involvement and patient-based evidence.