J Altern Complement Med. 2000 Dec; 6(6): 493-8.

Integrity and research: introducing the concept of dual blindness. how blind are double-blind clinical trials in alternative medicine?

Caspi O, Millen C, Sechrest L.

Department of Psychology, University of Arizona, Tucson, USA. ocaspi@ahsc.arizona.edu

Double-blind methodology is used in clinical studies to control for potential external or nonspecific influences such as belief and expectation, as well as to maintain as much objectivity as possible on the part of the researchers. Despite not being feasible in all medical disciplines, as in the case of some modalities of complementary and alternative medicine, there are numerous studies that spuriously claim its use. Distinctions and standards therefore need to be set to avoid misleading information. We propose a new term in research methodology, dual-blind, to describe a methodological alternative in which the caregiver is not blind but the patient and an external evaluator/investigator are. The term double-blind should be used strictly to describe a methodology in which both the patient and the caregiver are blind. Making the distinction between these two terms will result in more reliable reports of clinical trials and will support integrity in research.