Journal of clinical epidemiology
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Review Meta Analysis
Methodological quality and homogeneity influenced agreement between randomized trials and nonrandomized studies of the same intervention for back pain.
To determine the influence of methodological quality and homogeneity on the agreement between pairs of randomized trials (RCTs) and nonrandomized studies (NRSs) of the same interventions for low-back problems. Homogeneity was assessed regarding settings, population, interventions, and outcomes. ⋯ Pairs of low-quality studies disagreed more than pairs where at least one study was of high quality. However, pairs with similar settings, population, interventions, and outcomes showed higher agreement than pairs that were not as homogeneous.
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Meta Analysis
Trial methodology and patient characteristics did not influence the size of placebo effects on pain.
To determine whether trial-design, patient-type, or placebo-type factors influence the size of the placebo analgesic effect in clinical trials. ⋯ This study confirms the findings of previous researchers that, at present, the evidence for large placebo analgesic effects in clinical trials is lacking. Importantly, this analysis also establishes that larger placebo effects are not associated with particular aspects of the trial methodology, patient, or placebo type.