Improving the Reporting Quality of Nonrandomized Evaluations of Behavioral and Public Health Interventions: The TREND Statement (original) (raw)
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Randomized, Controlled Trials, Observational Studies, and the Hierarchy of Research Designs
New England Journal of Medicine, 2000
In the hierarchy of research designs, the results of randomized, controlled trials are considered to be evidence of the highest grade, whereas observational studies are viewed as having less validity because they reportedly overestimate treatment effects. We used published meta-analyses to identify randomized clinical trials and observational studies that examined the same clinical topics. We then compared the results of the original reports according to the type of research design.
Statistical Issues in Randomized Controlled Trials: an editorial
Electronic physician, 2018
Randomization is the bedrock of randomized controlled trials, which ensures the elimination of selection bias and also to some extent the homogenous distribution of covariates between the intervention arms. Randomization does not always guarantee the baseline balance, and hence makes the statistical analysis more complex. Several published clinical trials have employed test of significance to compare baseline measures between the groups. However, such practice has been criticized by several authors and CONSORT statement also discourages it. This overview discusses various statistical designs that were employed in published trials. Post intervention data (follow up score) comparison between the arms was common practice in published RCTs. However, this approach fails to adjust baseline imbalance. Both Change score and Percentage change methods adjust the baseline imbalance. Both of the approaches give precise estimates when there is a high correlation between baseline and follow-up score. However, when correlation is low they both give biased and less precise estimates of treatment effect. Analysis of covariance (ANCOVA) is a regression method, which maintains high statistical power and gives less biased and more precise estimates of treatment effect regardless of correlation level. Understanding strengths and limitations of different statistical designs of RCTs will prevent statistical errors, which can yield an accurate estimate of treatment effect.
Design of Randomized Controlled Trials Clarity of Study Objective
A major factor in the rapid advance of medical science over the past 50 years has been the development and refinement of the clinical research method known as the randomized controlled trial (RCT). A clinical trial is defined as a prospective scientific experiment that involves human subjects in whom treatment is initiated for the evaluation of a therapeutic intervention. In an RCT, each patient is assigned to receive a specific treatment intervention by a chance mechanism.
Journal of Public Health, 2013
Aim Rising concern for demonstrated real world comparative effectiveness has heightened interest in "pragmatic trials" design. Pragmatic trials investigate whether the efficacy, presumed or found in explanatory trials under ideal conditions, can also be detected under real world conditions, i.e. effectiveness. It is also recognized that 'real world' effects which are usually addressed in public health research gain growing interest in confirming the 'road capability' of results obtained under ideal study conditions. This paper demonstrates that studies under ideal or real world conditions use different methods, generate different information and cannot replace each other. Subjects and methods The PCT design meets four requirements of public health and of effectiveness research. It
BMC Medical Research Methodology, 2013
Background: Assessing the risk of bias of randomized controlled trials (RCTs) is crucial to understand how biases affect treatment effect estimates. A number of tools have been developed to evaluate risk of bias of RCTs; however, it is unknown how these tools compare to each other in the items included. The main objective of this study was to describe which individual items are included in RCT quality tools used in general health and physical therapy (PT) research, and how these items compare to those of the Cochrane Risk of Bias (RoB) tool. Methods: We used comprehensive literature searches and a systematic approach to identify tools that evaluated the methodological quality or risk of bias of RCTs in general health and PT research. We extracted individual items from all quality tools. We calculated the frequency of quality items used across tools and compared them to those in the RoB tool. Comparisons were made between general health and PT quality tools using Chi-squared tests. Results: In addition to the RoB tool, 26 quality tools were identified, with 19 being used in general health and seven in PT research. The total number of quality items included in general health research tools was 130, compared with 48 items across PT tools and seven items in the RoB tool. The most frequently included items in general health research tools (14/19, 74%) were inclusion and exclusion criteria, and appropriate statistical analysis. In contrast, the most frequent items included in PT tools (86%, 6/7) were: baseline comparability, blinding of investigator/assessor, and use of intention-to-treat analysis. Key items of the RoB tool (sequence generation and allocation concealment) were included in 71% (5/7) of PT tools, and 63% (12/19) and 37% (7/19) of general health research tools, respectively. Conclusions: There is extensive item variation across tools that evaluate the risk of bias of RCTs in health research. Results call for an in-depth analysis of items that should be used to assess risk of bias of RCTs. Further empirical evidence on the use of individual items and the psychometric properties of risk of bias tools is needed.
Revista Pesquisa em Fisioterapia
JUSTIFICATIVA: Ensaios clínicos randomizados (ECR) são o padrão ouro para desenho experimental de estudo ou ensaio clínico. Apenas por meio de uma investigação do tipo ECR é possível avaliar e demonstrar a relação de causa-e-efeito entre um conjunto de variáveis independentes e dependentes. O ECR adicionou vantagens em relação aos outros modelos experimentais, principalmente devido à presença de um grupo controle. Existem várias críticas à validade interna das pesquisas em saúde, incluindo preconceitos e desvantagens que são apontadas para seu descrédito. OBJETIVO: O objetivo do presente estudo é informar características, vantagens, desvantagens e desvios deste método científico. MATERIAL E MÉTODOS: Análise crítica de método científico com base em revisão narrativa da literatura. Foi consultada a base de dados Medline por meio dos portais PubMed e Scopus, sem data de início e até julho de 2020, para extração das informações relativas aos ECR. Apenas artigos de língua inglesa foram i...
Research Synthesis Methods, 2012
Non-randomized studies may provide valuable evidence on the effects of interventions. They are the main source of evidence on the intended effects of some types of interventions and often provide the only evidence about the effects of interventions on long-term outcomes, rare events or adverse effects. Therefore, systematic reviews on the effects of interventions may include various types of non-randomized studies. In this second paper in a series, we address how review authors might articulate the particular non-randomized study designs they will include and how they might evaluate, in general terms, the extent to which a particular non-randomized study is at risk of important biases. We offer guidance for describing and classifying different non-randomized designs based on specific features of the studies in place of using non-informative study design labels. We also suggest criteria to consider when deciding whether to include non-randomized studies. We conclude that a taxonomy of study designs based on study design features is needed. Review authors need new tools specifically to assess the risk of bias for some non-randomized designs that involve a different inferential logic compared with parallel group trials.