Placebo - Efficacy and Adverse Effects in Controlled Clinical Trials

Abstract

Treatment with placebo is frequently effective and cannot therefore be considered as "non-treatment". Placebo effects can only be quantified by direct comparison with "non-treatment". Like active treatment, treatment with placebo is frequently accompanied by adverse drug reactions. Placebo adverse effects are often disease- and active treatment-specific. The effects and adverse effects of a placebo need to be known before the effects of active treatment in controlled clinical trials can be assessed. The mechanisms of placebo effects are many and varied (e.g. endorphin release, conditioning). Since the use of drugs without regard to evidence-based medicine (prescription of drugs without proven efficacy = pseudoplacebos) may clearly also result in serious adverse effects, such practice may not only be non-beneficial but may even be harmful.

Meta‐analysis: incidence of endoscopic gastric and duodenal ulcers in placebo arms of randomized placebo‐controlled NSAID trials

“…The placebo effect contributes to the observed treatment effect and differs according to clinical conditions and interventions 57 . Therefore, the effects of a placebo should be considered before the effects of an active treatment in placebo‐controlled clinical trials can be properly assessed 3,58,59 . The more the placebo mimics the active treatment, the less the difference that will be detected between placebo and an active treatment.…”

“…The GI safety profile of NSAIDs is often evaluated by comparison with placebo in randomized controlled trials (RCTs). However, a ‘placebo effect’ does not mean that there is ‘no effect’ and placebo cannot therefore be considered as ‘no treatment’ 3–5 . Moreover, approximately one‐fifth of healthy subjects have some degree of adverse experiences when taking placebo 6 .…”

The placebo effect, sleep difficulty, and side effects: a balanced placebo model

“…Participants in the placebo arms of clinical trials often report side effects that mirror the warnings they received (Amanzio et al, 2009;Weihrauch & Gauler, 1999). Chemotherapy patients who have higher expectancy of nausea report experiencing greater nausea posttreatment (Colagiuri et al, 2013;Colagiuri et al, 2008;Colagiuri & Zachariae, 2010;Roscoe et al, 2010;Shelke et al, 2008;Sohl et al, 2009).…”

Expectancy, Self-Efficacy, and Placebo Effect of a Sham Supplement for Weight Loss in Obese Adults

“…2,3 A few studies have reported on placebo effects in pharmacologic therapy for obesity 4,5 and cardiovascular diseases. 6,7 However, mechanisms of placebo effects have not been fully elucidated. If present, placebo effects may be due to altered expectancies regarding treatment efficacy, altered behavior leading to improved lifestyle, or, more directly, altered physiology as a result of exposure to the placebo.…”