OBJECTIVE To determine whether trial-design, patient-type, or placebo-type factors influence the size of the placebo analgesic effect in clinical trials. STUDY DESIGN AND SETTING Trials that measured pain outcomes in Hróbjartsson and Gøtzsche's meta-analysis were retrieved and coded for eight factors potentially predictive of placebo effect size. Random effects meta-regression was used to exp...

The placebo effect is seen in patients who have been the target of intervention believed to lack specific action. This effect seems to be an important, and possibly the only, contribution to the positive effect of alternative medicine sometimes reported. The risks involved in the uncritical utilization of the placebo effect are, however, great and must be carefully considered. Most of the infor...

The paper examines the placebo effect in sports performance. The possibility that the placebo effect is a more common phenomenon than the quantity of published research would suggest is briefly addressed. It is suggested that the placebo control design often used in sports performance research masks any placebo effects and thus presents a false picture of the mechanisms underlying performance-e...

BACKGROUND It has been argued that placebos may not have important clinical impacts in general. However, there is increasing evidence of a publication bias among trials published in journals. Therefore, we explored the potential for publication bias in randomized trials with active treatment, placebo, and no-treatment groups. METHODS Three-armed randomized trials of acupuncture, acupoint stim...

purpose: to evaluate the effect of intravitreal triamcinolone acetonide (ivt) on clinical, angiographic, and optical coherence tomographic parameters in refractory diabetic macular edema (dme). methods: in a double-masked placebo-controlled randomized clinical trial, 88 eyes of 61 patients with dme refractory to previous laser therapy or not suitable for such treatment were included in the stud...

BACKGROUND It is an inherent assumption in randomised controlled trials that the drug effect can be estimated by subtracting the response during placebo from the response during active drug treatment. OBJECTIVE To test the assumption of additivity. The primary hypothesis was that the total treatment effect is smaller than the sum of the drug effect and the placebo effect. The secondary hypoth...

Placebo exhibits beneficial effects on pain perception in human experimental studies. Most of these studies demonstrate that placebo significantly decreased neural activities in pain modulatory brain regions and pain-evoked potentials. This study examined placebo analgesia-related effects on spontaneous brain oscillations. We examined placebo effects on four order-fixed 20-min conditions in two...

Using causal diagrams, a formal research methodology, we analyzed several definitions of placebo and the placebo effect. We conclude that placebo is an ambiguous, redundant term and that the so-called placebo effect conceals far more interesting effects that are attributed to the patient's expectation. Biomedical research will benefit from abandoning the term placebo effect and focusing instead...

BACKGROUND It is the gold standard to use a placebo treatment as the control group in prospective randomized controlled trials (RCTs). Although placebo-controlled trials can reveal an effect of an active treatment, the pure effect of a placebo treatment alone has never been presented or evaluated. No evidence-based, placebo-therapeutic options are currently available, and no placebo-controlled ...