The significance of characteristics of the provider as well as the treatment. Controlled trials of surgical procedures have been done less frequently than studies of medications because it is much more difficult to standardize the process of surgery. Surgery depends to some degree on the skills and training of the surgeon and the specific environment and support team available to the surgeon. A surgical procedure in the hands of a highly skilled, experienced surgeon is different from the same procedure in the hands of an inexperienced and unskilled surgeon (Hu et al., 2003). For many CAM modalities, it is similarly difficult to separate the effectiveness of the treatment from the effectiveness of the person providing the treatment. Indeed, the idea of conceptual separation of treatment and provider would seem foreign for those modalities. The designs of studies of CAM modalities that involve the active participation of a “healer” must incorporate the characteristics of that person as well as the characteristics of the treatment being applied by that person.

Different underlying theoretical and diagnostic systems. Concepts of levels of evidence and evidence-based medicine in conventional medicine rely on a generally accepted diagnostic classification system that is embodied in formal diagnostic systems like the International Classification of Diseases-Version 10 (ICD-10) and the Diagnostic and Statistical Manual-Version IV (DSM-IV). It will be somewhat challenging to apply similar study designs, measures of clinical endpoints, and standards of evidence to therapies that use different diagnostic systems and therefore to identify different sets of patients as the group to whom the study results apply. It will be even more challenging to apply these concepts to any CAM modalities that emphasize the uniqueness of each individual patient and that patient’s complex of symptoms and to avoid diagnostic classifications entirely.

Endpoints like feelings of emotional or spiritual well-being that are difficult to measure. The most important dependent variables in many CAM modalities will be hard to define in objective terms and may vary from patient to patient (Jonas and Linde, 2002). A study of whether acupuncture is effective for patients with cancer may not be able to focus on mortality or shrinkage of tumors but, instead may have to focus on questions of whether the patients feel relief of pain and other symptoms and whether they feel more in control of their illness and are better able to manage the cancer along with their other daily tasks.

Difficult or impossible to conduct double-blind trials with some modalities. The concept of blinding in which the patients and the treating clinicians participating in clinical trials do not know what treatment the