1. 2017;20;363-386Therapeutic Role of Placebo: Evolution of a New Paradigm in Understanding Research and Clinical Practice
   Comprehensive Review
   Alan D. Kaye, MD, PhD, Standiford Helm II, MD, Joshua A. Hirsch, MD, Laxmaiah Manchikanti, MD, and Mark V. Boswell, MD, PhD.

Research into interventional techniques in managing chronic spinal pain continues to be challenging, mystifying, confusing, and biased. Insight, or lack thereof, into placebo and nocebo phenomena contributes mightily to these difficulties. Unfortunately, placebo-nocebo responses are the subject of numerous controversies and challenges from not only a research perspective, but also clinical perspective. While interventionalists consider the biggest threat to interventional pain management research is inappropriate and outdated interpretation of the data, a greater problem is the misuse of the placebo response in research, with the declaration that all and everything as a placebo effect: with a misinterpretation of the nature of the placebo the, associated conclusions can be inaccurate.

Researchers have been aware of placebo and nocebo effects for decades, even though misunderstandings and misgivings continue to be seen in scientific studies. In simplistic terms, placebo and nocebo had been understood to indicate improving or worsening of symptoms that occur during treatment with placebo/nocebo drugs or modalities. However, research has demonstrated that such terminology does not necessarily reflect “true” placebo effect or nocebo response. These effects are based on numerous factors, including natural course of a disease, spontaneous remission, regression to the mean, and a multitude of other conceptual, explanatory, and moral challenges. In modern clinical research, a neutral substance called placebo has been mainly used as a comparison factor rather than being studied itself, while the nocebo response has only been minimally studied.

A major misconception involves active placebo, a concept that has been extended beyond the administration of inert substances. The definition of active placebo of an active agent given to a patient, even though the pharmacologic action of the active agent is not known to be beneficial, has been converted to conveniently change many of the treatments which are effective on their own to be defined as placebos, often leading to conclusions that none of the interventions are effective.

This review focuses on a multitude of controversies surrounding placebo and nocebo phenomena in research and clinical applications. The discussion includes a focus on unsolved, forgotten, and ignored features of placebo responses in medicine, and provides an appropriate understanding of placebo and nocebo phenomena in interventional pain management. To that effect, this review also describes therapeutic placebos, research with open placebos, and improvements in understanding clinical applications of present interventional pain management research.

Keywords: Placebo effect, nocebo response, placebo analgesia, interventional techniques, active control trials, active placebos