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The National Institutes of Health (NIH) defines a clinical trial as “A research study in which one or more human subjects are prospectively assigned to one or more interventions (which may include placebo or other control) to evaluate the effects of those interventions on health-related biomedical or behavioral outcomes.” (NOT-OD-15-015). NIH defines a mechanistic study (which can be a type of clinical trial) as: “A mechanistic study is designed to understand a biological or behavioral process, the pathophysiology of a disease, or the mechanism of action of an intervention.”

NCCIH recognizes a difference between clinical trials that are designed to answer specific questions about the clinical effect of interventions and mechanistic studies that have the primary goal of understanding how an intervention works.

  • A mechanistic study is defined as one designed to understand the mechanism of action of an intervention, a biological process, or the pathophysiology of a disease.
  • A clinical outcome study is defined as one with the objective of determining the clinical safety, tolerability, feasibility, efficacy, and/or effectiveness of pharmacologic, nonpharmacologic, behavioral, biologic, surgical, or device (invasive or non-invasive) interventions.

Clinical trials are particularly important to NCCIH. Complementary and integrative health interventions are widely used by the American public (see Complementary, Alternative, or Integrative Health: What’s In a Name?) but are often used with scare evidence of efficacy. NCCIH sees substantial promise in many of these interventions but recognizes that the evidence supporting their use is often incomplete. The NCCIH clinical trial NOFOs will help to address gaps in current research and build a strong evidence base. 

With the continuum of available NCCIH clinical trial NOFOs, we support investigators working on the “building blocks” that bridge the gap from basic research to high-impact clinical trials. We provide pathways via these NOFOs to support all developmental steps that may lead to major clinical trials on complementary and integrative health approaches. Applications to nearly all the NCCIH clinical trial NOFOs listed in the Mind and Body and Natural Products Clinical Trials tables will be assessed by special emphasis review panels familiar with our research priorities and the goals of each NOFO. 



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