The continued widespread use of individual and multiple CAM therapies underscores the need to rigorously evaluate the safety, efficacy, and cost-effectiveness of these approaches, according to the study’s lead author Hilary Tindle, Harvard Medical School (HMS) research fellow, and co-author David Eisenberg, director of the Division for Research and Education in Complementary and Integrative Medical Therapies and the Osher Institute at HMS. The study results appeared in the January/February 2005 issue of the medical journal Alternative Therapies in Health and Medicine. The study compared results of the National Health Interview Survey in 2002 and a survey conducted by researchers at HMS (Eisenberg et al.) in 1997. The two surveys were similar but not identical. Prior to this study, there had been no head-to-head comparison using a common definition of CAM. The largest change was a 50 percent jump in the use of herbal supplements, growing over the five years from 12.1 percent of adults reporting usage in 1997 to 18.6 percent — or 38 million adults — in 2002. The practice of yoga increased 40 percent over the same period, growing from 3.7 percent in 1997 to 5.1 percent– over 10 million adults- – in 2002. This work was made possible in part by grants from the National Center for Complementary and Alternative Medicine and by private foundation grants.