Readers are invited to visit a recent addition to the chapter Monitoring Intervention Fidelity and Adaptations in the Living Textbook. The new content offers considerations for study teams who are preparing to track the fidelity of an embedded—and potentially complex—clinical intervention. Considerations include identifying which features of the intervention (i.e., functions) are so essential to its effectiveness that modifying them could negatively affect the study’s outcomes and impact. Equally important is knowing which elements (i.e., forms) can be adapted to accommodate contextual factors or local needs without affecting fidelity. The section provides an introduction and link to methodology standards for complex interventions recently developed by the Patient-Centered Outcomes Research Institute (PCORI).

“Functions of a complex intervention represent a purpose or goal, while forms are the tools or processes used to achieve a function. Identifying forms and functions allows adapted complex interventions to retain a level of standardization and integrity in design.” (Hill et al. 2020)