The document presents a series of 23 case studies evaluating various types of research against the NIH definition of a clinical trial, providing rationales for each determination. It illustrates that a study qualifies as a clinical trial if it involves human subjects, prospective assignment to interventions (including behavioral, biomedical, or diagnostic procedures), and the assessment of health-related biomedical or behavioral outcomes. Several cases are identified as clinical trials because they meet these criteria, such as studies testing new drugs or interventions, randomly assigning subjects to different health-related strategies, or evaluating changes in health status. Conversely, studies are excluded from this classification when they rely solely on de-identified biological samples, only assess device feasibility without human intervention, or focus on outcomes not considered health-related.
The document also highlights distinctions in ambiguous cases. For example, studies that prospectively assign interventions but do not measure health-related outcomes, or those that lack prospective assignment even with health-related outcomes, do not qualify as clinical trials. Further, some research using diagnostic devices or seeking mechanistic understanding without intended health improvement also falls outside the definition. By systematically reviewing these case studies, the document clarifies the boundaries of the NIH clinical trial definition, supporting accurate classification in accordance with regulatory and ethical guidelines.
