Journal of clinical epidemiology
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Progress in understanding the placebo effect and its clinical significance depends on conceptual clarification of this elusive phenomenon and critical appraisal of research bearing on the influence of placebo interventions on clinical outcomes. Here we locate the placebo effect within a typology of modes of healing, distinguish between the observed placebo response in randomized controlled trials and the placebo effect, and examine critically a recent meta-analysis of clinical trials that challenges the reality of the placebo effect.
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Various prognostic models have been developed to predict outcome after traumatic brain injury (TBI). We aimed to determine the validity of six models that used baseline clinical and computed tomographic characteristics to predict mortality or unfavorable outcome at 6 months or later after severe or moderate TBI. ⋯ Our findings emphasize the need for external validation of prognostic models. The satisfactory discrimination indicates that logistic regression models, developed on large samples, can be used for classifying TBI patients according to prognostic risk.
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Comparative Study
Estimated progression rates in three United Kingdom hepatitis C cohorts differed according to method of recruitment.
To estimate hepatitis C virus (HCV) progression rates between disease stages prior to cirrhosis, using data from liver biopsies in three observational cohorts. To demonstrate how the method of cohort recruitment can influence the estimation of HCV-progression rates. ⋯ Researchers using estimates of disease progression should be aware that the method of cohort recruitment has considerable influence on the progression rates that are derived.
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Comparative Study
A minimal clinically important difference was derived for the Roland-Morris Disability Questionnaire for low back pain.
To compare methods commonly used to derive minimal important differences and recommend a rule for defining patients as clinically improved on the low back pain-specific Roland-Morris Disability Questionnaire (RMDQ). ⋯ A minimal clinically important difference is derived that is clinically relevant, incorporates the measurement error of the RMDQ, and allows subjects with different grades of severity to improve.