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; · 5.43 Impact Factor
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ABSTRACT: Although response to colchicine has been proposed as one of the diagnostic criteria in patients with Familial Mediterranean fever (FMF), the validity of this response has not been validated. The aim of this study was to assess the efficacy of the response to colchicine and to evaluate the extent of the effect of placebo. A double-blind randomized placebo-controlled trial with a cross-over design was conducted. The frequency of FMF attacks, the disease score, physical examination, and acute phase reactants were assessed at 0, 3, and 6 months. Blood samples were collected for complete blood count (CBC), erythrocyte sedimentation rate (ESR), levels of serum C-reactive protein (CRP) and serum amyloid A (SAA), and MEFV mutation analysis in 79 patients with a preliminary diagnosis of FMF. Patients were randomly allocated to receive either drug A or drug B in a double-blind fashion. The designated drug was switched at 3 months. Patients taking colchicine had less frequent FMF attacks (median 0) and lower FMF disease score (median 0) when compared to those on placebo (median 1 and 3, respectively) (p = 0.002 and p = 0.007, respectively). In genetically confirmed FMF patients, median attack number and median disease score was 0 under colchicine treatment, whereas these parameters were significantly higher in the placebo group (median 2 and 8, respectively) (p = 0.007 and p = 0.02, respectively) suggesting that colchicine is more effective than placebo in reducing attacks and disease score. Positive and negative predictive values were 70.2 and 37.5 %, respectively. During the placebo period, patients had less FMF attacks when compared to that of the pre-study period (median 2 vs 6, respectively) (p < 0.001). The high false positive rate raises concerns for considering the colchicine response test as diagnostic for FMF. The role of placebo on the attacks of periodic fever syndromes needs to be further investigated.Clinical Rheumatology 04/2014; 33(7). · 1.77 Impact Factor
- Brain Stimulation 09/2014; · 5.43 Impact Factor