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Meta-analytic Approach (meta-analytic + approach)
Selected AbstractsDoes elimination of placebo responders in a placebo run-in increase the treatment effect in randomized clinical trials?DEPRESSION AND ANXIETY, Issue 1 2004A meta-analytic evaluation Abstract The use of a placebo run-in phase, in which placebo responders are withdrawn from a study before random assignment to treatment condition, has been criticized as favoring the active treatment in clinical trials. We compared the effect size of randomized, placebo-controlled clinical trials (in the treatment of depression with selective serotonin reuptake inhibitors [SSRIs]) that include a placebo run-in phase with those that do not, using a meta-analytic approach. This study differed from earlier meta-analytic studies in that it considered only SSRIs and included only studies using continuous measures of depression, allowing for a more refined assessment of effect size. An extensive literature search identified 43 datasets published between 1980 and 2000 comparing placebo with SSRI and using a continuous measure of depression (usually the Hamilton Depression Rating Scale). We included only studies of at least 6 weeks' duration focusing on treatment for primary acute major depression in adults 18,65 years of age. Studies focusing on depression in specific medical illnesses were not included. Analysis of efficacy was based on 3,047 subjects treated with an SSRI antidepressant and 3,740 subjects treated with a placebo. There was no statistically significant difference in effect size between the clinical trials that had a placebo run-in phase followed by withdrawal of placebo responders and those trials that did not. Despite the lack of a statistically significant difference between studies of withdrawing early placebo responders and those not using this procedure, this approach is likely to continue to be used widely because it produces large absolute effect sizes. It is recommended that future studies clearly describe these procedures and report the number of subjects dropped from the study for early placebo response and other reasons. Depression and Anxiety 19:10,19, 2004. 2004 Wiley-Liss, Inc. [source] Estimation of the burden of active and life-time epilepsy: A meta-analytic approachEPILEPSIA, Issue 5 2010Anthony K. Ngugi Summary Purpose:, To estimate the burden of lifetime epilepsy (LTE) and active epilepsy (AE) and examine the influence of study characteristics on prevalence estimates. Methods:, We searched online databases and identified articles using prespecified criteria. Random-effects meta-analyses were used to estimate the median prevalence in developed countries and in urban and rural settings in developing countries. The impact of study characteristics on prevalence estimates was determined using meta-regression models. Results:, The median LTE prevalence for developed countries was 5.8 per 1,000 (5th,95th percentile range 2.7,12.4) compared to 15.4 per 1,000 (4.8,49.6) for rural and 10.3 (2.8,37.7) for urban studies in developing countries. The median prevalence of AE was 4.9 per 1,000 (2.3,10.3) for developed countries and 12.7 per 1,000 (3.5,45.5) and 5.9 (3.4,10.2) in rural and urban studies in developing countries. The estimates of burden for LTE and AE in developed countries were 6.8 million (5th,95th percentile range 3.2,14.7) and 5.7 million (2.7,12.2), respectively. In developing countries these were 45 (14,145) million LTE and 17 (10,133) million AE in rural areas and 17 (5,61) million LTE and 10 (5,17) million AE in urban areas. Studies involving all ages or only adults showed higher estimates than pediatric studies. Higher prevalence estimates were also associated with rural location and small study size. Conclusions:, This study estimates the global burden of epilepsy and the proportions with AE, which may benefit from treatment. There are systematic differences in reported prevalence estimates, which are only partially explained by study characteristics. [source] Involvement of the inferior frontal junction in cognitive control: Meta-analyses of switching and Stroop studiesHUMAN BRAIN MAPPING, Issue 1 2005Jan Derrfuss Abstract There is growing evidence that a specific region in the posterior frontolateral cortex is involved intimately in cognitive control processes. This region, located in the vicinity of the junction of the inferior frontal sulcus and the inferior precentral sulcus, was termed the inferior frontal junction (IFJ). The IFJ was shown to be involved in the updating of task representations and to be activated commonly in a within-subject investigation of a task-switching paradigm, the Stroop task, and a verbal n-back task. Here, we investigate the involvement of the IFJ in cognitive control by employing a meta-analytic approach. Two quantitative meta-analyses of functional magnetic resonance imaging (fMRI) studies were conducted. One meta-analysis included frontal activations from task-switching, set-shifting, and stimulus,response (S,R) reversal studies, the other included frontal activations from color,word Stroop studies. Results showed highly significant clustering of activations in the IFJ in both analyses. These results provide strong evidence for the consistent involvement of the IFJ in both switching and Stroop paradigms. Furthermore, they support our concept of areal specialization in the frontolateral cortex, which posits that it is not only the middorsolateral part that plays an important role in cognitive control, but also the IFJ. Finally, our results demonstrate how quantitative meta-analyses can be used to test hypotheses about the involvement of specific brain regions in cognitive control. Hum Brain Mapp 25:22,34, 2005. © 2005 Wiley-Liss, Inc. [source] A prospective meta-analytic approach in a multisite study of homelessness preventionNEW DIRECTIONS FOR EVALUATION, Issue 94 2002Steven Banks This chapter describes a technique based on meta-analysis for analyzing data from multisite studies. [source] Magnetic resonance imaging as a potential surrogate for relapses in multiple sclerosis: A meta-analytic approach,ANNALS OF NEUROLOGY, Issue 3 2009Maria Pia Sormani MscStat Objective The aim of this work was to evaluate whether the treatment effects on magnetic resonance imaging (MRI) markers at the trial level were able to predict the treatment effects on relapse rate in relapsing-remitting multiple sclerosis. Methods We used a pooled analysis of all the published randomized, placebo-controlled clinical trials in relapsing-remitting multiple sclerosis reporting data both on MRI variables and relapses. We extracted data on relapses and on MRI "active" lesions. A regression analysis weighted on trial size and duration was performed to study the relation between the treatment effect on relapses and the treatment effect on MRI lesions. We validated the estimated relation on an independent set of clinical trials satisfying the same inclusion criteria but with a control arm other than placebo. Results A set of 23 randomized, double-blind, placebo-controlled trials in relapsing-remitting multiple sclerosis was identified, for a total of 63 arms, 40 contrasts, and 6,591 patients. A strong correlation was found between the effect on the relapses and the effect on MRI activity. The adjusted R2 value of the weighted regression line was 0.81. The regression equation estimated using the placebo-controlled trials gave a satisfactory prediction of the treatment effect on relapses when applied to the validation set. Interpretation More than 80% of the variance in the effect on relapses between trials is explained by the variance in MRI effects. Smaller and shorter phase II studies based on MRI lesion end points may give indications also on the effect of the treatment on relapse end points. Ann Neurol 2009;65:268,275 [source] Which clinical factors predict response to prophylactic lithium?BIPOLAR DISORDERS, Issue 5 2005A systematic review for bipolar disorders Objectives:, The aim of this study was to systematically integrate the available evidence on response prediction to prophylactic lithium based on clinical factors. Methods:, Each clinical variable that was related to lithium response in at least one prior study was examined with respect to response prediction. If several studies were located for the same variable, results were integrated using the meta-analytic approach as suggested by DerSimonian and Laird which was developed for substantial heterogeneity in primary studies. Results:, Of 42 potential clinical predictors investigated, five variables were identified as possible response predictors of prophylactic lithium: [1] An episodic pattern of mania-depression-interval, and [2] a high age of illness onset were identified as potentially protective against a recurrence under lithium. [3] A high number of previous hospitalizations, [4] an episodic pattern of depression-mania-interval, and [5] continuous cycling were identified as potential risk factors. Six further variables were found to be significantly related to lithium response, though calculation of fail-safe numbers indicates that current evidence is not sufficient to hold these variables as reliable predictors of lithium response. All effect-sizes relating clinical predictors to response were small to moderate. Conclusions:, Although a few variables are quite robustly supported as response-predictors in this review, a more in-depth analysis of each potential predictor is needed. As none of the potential predictors had a very strong impact on response, prediction of lithium response should be based on a multitude of variables. [source] The Evolution of Clinical SignificanceCLINICAL PSYCHOLOGY: SCIENCE AND PRACTICE, Issue 4 2001William C. Follette During the evolution of the concept of clinical significance, there has been a continuing dialog about and refinement of the construct. In this issue Sheldrick, Kendall, and Heimberg apply Kendall, Marrs-Carcia, and Sheldrick's method of equivalency testing and normative comparisons to treatments for conduct disorders. This method has important advantages over traditional meta-analytic approaches. However, analyzing results at the level of group means rather than the individual level loses significant information and can be misleading. Problems in reporting practices and inadequate attention to measurement issues continue to make efforts to assess the clinical importance of studies difficult. We renew a call for the assessment of clinical significance at the individual level of analysis, suggesting it is necessary to guide to selection of empirical supported treatments and in advancing theoretically driven programs of psychotherapy outcome research. [source] | |||||||||||||||||||