Aromatherapy and Essential Oils (PDQ®): Complementary and alternative medicine - Health Professional Information [NCI] - Summary of the Evidence for Aromatherapy and Essential Oils
To assist readers in evaluating the results of human studies of complementary and alternative medicine (CAM) treatments for people with cancer, the strength of the evidence (i.e., the levels of evidence) associated with each type of treatment is provided whenever possible. To qualify for a level of evidence analysis, a study must:
- Be published in a peer-reviewed scientific journal.
- Report on a therapeutic outcome or outcomes, such as tumor response, improvement in survival, or measured improvement in quality of life.
- Describe clinical findings in enough detail that a meaningful evaluation can be made.
Separate levels of evidence scores are assigned to qualifying human studies on the basis of statistical strength of the study design and scientific strength of the treatment outcomes (i.e., endpoints) measured. The resulting two scores are then combined to produce an overall score. A table showing the levels of evidence scores for qualifying human studies cited in this summary is presented below. For an explanation of the scores and additional information about levels of evidence analysis of CAM treatments for people with cancer, refer to Levels of Evidence for Human Studies of Cancer Complementary and Alternative Medicine.