is a clearly defined idea or construct that forms the foundation for measurement in medical product development and evaluation. Within the U.S. Food and Drug Administration (FDA) framework, a COI identifies the specific clinical or patient-centered aspect (such as a symptom, function, or health-related quality of life element) that a medical product is intended to affect. It guides what should be measured in clinical trials to demonstrate a product’s safety, efficacy, and impact on public health.