OPEN a ACCESS Freely available online PI oS one Clinical Trial Placebos without Deception: A Randomized Controlled Trial in Irritable Bowel Syndrome Ted J. Kaptchuk''2•, Elizabeth Friedlander', John M. Kelley3'4, M. Norma Sanchez', Efi Kokkotou', Joyce P. Singer2, Magda Kowalczykowskil , Franklin G. Millers, Irving Kirsch's, Anthony J. Lembo' 1 Beth Israel Deaconess Medical Center. Harvard Medical School, Boston, Massachusetts. United States of America, 2 Osher Research Center, Harvard Medical School, Boston, Massachusetts. United States of America, 3 Psychology Department, Endicott College, Beverly, Massachusetts, United States of America, 4 Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America, 5 Department of Bioethks, National Institutes of Health, Bethesda, Maryland, United States of America, 6 Department of Psychology, UnNersity of Hull, Hull, United Kingdom Abstract Background: Placebo treatment can significantly influ- ence subjective symptoms. However, it is widely believed that response to placebo requires concealment or deception. We tested whether open-label placebo (non- deceptive and non-concealed administration) is superior to a no-treatment control with matched patient-provider interactions in the treatment of irritable bowel syndrome (IBS). Methods: Two-group, randomized, controlled three week trial (August 2009-April 2010) conducted at a single academic center, involving 80 primarily female (70%) patients, mean age 47:18 with IBS diagnosed by Rome III criteria and with a score .--2150 on the IBS Symptom Severity Scale (IBS-SSS). Patients were randomized to either open-label placebo pills presented as "placebo pills made of an inert substance, like sugar pills, that have been shown in clinical studies to produce significant improvement in IBS symptoms through mind-body self- healing processes" or no-treatment controls with the same quality of interaction with providers. Th