Abstract
BACKGROUND: A process evaluation systematically examines how an intervention is delivered, including activities, procedures, and contextual factors influencing implementation. Existing process evaluation frameworks were primarily developed for education or public health settings, and do not reflect the complexity of critical care trials, which often involve medical technologies, high-acuity patients, and multidisciplinary care in dynamic environments. This study aimed to develop a framework (the POETIC (PrOcess Evaluation of Trials In Critical care) framework) to guide researchers in designing and conducting process evaluations that capture delivery quality and contextual understanding specific to critical care settings. METHODS: Framework development began in 2015 and followed an iterative, multi-phase process. Phase 1 included structured literature reviews to identify a) existing process evaluation frameworks and dimensions, and b) critical care trials with embedded process evaluations. Both reviews were updated in 2025 to reflect POETIC's usage and ensure continued relevance. Phase 2 involved expert consultations with trialists, clinicians, and methodologists to refine framework dimensions. RESULTS AND CONCLUSIONS: Four key process evaluation frameworks and two U.K.-based critical care trials informed initial development. The 2025 update identified five additional U.K. trials, four of which applied POETIC, supporting its relevance and applicability. Expert consensus identified five core dimensions:• Context (Unit Culture, Organizational Structure, Resources, Usual Practice, Attitudes and Perceptions)• Fidelity (extent to which the intervention is delivered as intended)• Dose (amount of the intended intervention delivered and received)• Reach (extent to which the target population is exposed to, or engages with, the intervention)• Quality of Delivery (integrative measure of Fidelity, Dose, and Reach)The framework includes recommended methods such as checklists, interviews, routine trial data, and observations. It was iteratively refined to enhance usability and adaptability and has since been applied in multiple U.K.-based perioperative and critical care trials, demonstrating its utility in U.K. ICU settings. The POETIC framework supports structured evaluation of delivery quality and context in critical care trials, improving trial interpretation and advancing intervention design, delivery, and real-world applicability. Distinctively, POETIC operationalizes ICU-specific Context sub-constructs and provides a prespecified composite Quality of Delivery index to link intervention delivery to outcomes.