Placebo treatment versus no treatment.
ABSTRACT Placebo interventions are often believed to improve patient reported and observer reported outcomes, but this belief is not based on evidence from randomised trials that compare placebo with no treatment.
To assess the effect of placebo interventions.
We searched the Cochrane Controlled Trials Register (The Cochrane Library, issue 3, 1998), MEDLINE (Jan 1966 to Dec 1998), EMBASE (Jan 1980 to Dec 1998), Biological Abstracts (Jan 1986 to Dec 1998), PsycLIT (Jan 1887 to Dec 1998). Experts on placebo research were contacted and references in the included trials were read.
Randomised placebo trials with a no-treatment control group investigating any health problem were included.
Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information.
Outcome data were available in 114 out of 130 included trials, investigating 40 clinical conditions. Outcomes were binary in 32 trials (3795 patients) and continuous in 82 (4730 patients). We found no statistically significant pooled effect of placebo in studies with binary outcomes, relative risk 0.95 (95 per cent confidence interval 0.88 to 1.02). The pooled relative risk for subjective (patient reported) outcomes was 0.95 (0.86 to 1.05) and for objective (observer reported) outcomes 0.91 (0.80 to 1.04). There was statistically significant heterogeneity (P < 0.03), but no evidence of sample size bias (P = 0.56). We found an overall positive effect of placebo treatments in trials with continuous outcomes, standardised mean difference -0.28 (95 per cent confidence interval -0.38 to -0.19). The standardised mean difference for subjective outcomes was -0.36 (-0.47 to -0.25), whereas no statistically significant effect was found for objective outcomes, standardised mean difference -0.12 (-0.27 to 0.03). There was statistically significant heterogeneity (P < 0.001), and evidence of sample size bias (P = 0.05). There was no statistically significant effect of placebo interventions in eight out of nine clinical conditions investigated in three trials or more (nausea, relapse in prevention of smoking and depression, overweight, asthma, hypertension, insomnia and anxiety), but confidence intervals were wide. There was a modest apparent analgesic effect of placebo interventions, standardised mean difference -0.27 (-0.40 to -0.15), but also a substantial risk of bias.
There was no evidence that placebo interventions in general have clinically important effects. A possible moderate effect on subjective continuous outcomes, especially pain, could not be clearly distinguished from bias.
Article: One Swallow Does Not a Summer MakeBrain Stimulation 10/2014; 7(6). DOI:10.1016/j.brs.2014.09.004 · 5.43 Impact Factor
Brain Stimulation 09/2014; 7(6). DOI:10.1016/j.brs.2014.09.011 · 5.43 Impact Factor
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ABSTRACT: Context effects are described as effects of a given treatment, not directly caused by the treatment itself, but rather caused by the context in which treatment is delivered. Exercise is a recommended core treatment in clinical guidelines for musculoskeletal disorders. Although moderately effective overall, variation is seen in size of response to exercise across randomised controlled trial (RCT) studies. Part of this variation may be related to the fact that exercise interventions are performed in different physical environments, which may affect participants differently. The study aims to investigate the effect of exercising in a contextually enhanced physical environment for 8 weeks in people with knee or hip pain. The study is a double-blind RCT. Eligible participants are 35 years or older with persisting knee and/or hip pain for 3 months. Participants are randomised to one of three groups: (1) exercise in a contextually enhanced environment, (2) exercise in a standard environment and (3) waiting list. The contextually enhanced environment is located in a newly built facility, has large windows providing abundant daylight and overlooks a recreational park. The standard environment is in a basement, has artificial lighting and is marked by years of use; that is, resembling many clinical environments. The primary outcome is the participant's global perceived effect rated on a seven-point Likert scale after 8 weeks exercise. Patient-reported and objective secondary outcomes are included. The Regional Scientific Ethical Committee for Southern Denmark has approved the study. Study findings will be disseminated in peer-reviewed publications and presented at national and international conferences. NCT02043613. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.BMJ Open 01/2015; 5(3):e007701. DOI:10.1136/bmjopen-2015-007701 · 2.06 Impact Factor