Summary
Nowadays the Randomised Controlled Trial (RCT) is seen as the gold standard for estimating the effectiveness of an observed intervention, achieving the highest hierarchy of evidence of primary research settings. Its study design basically includes two groups of patients, an intervention group and a control group; patients are randomly allocated to these two groups. After intervention or control intervention took place, predefined outcomes are quantified and compared in the two groups. The study design aims at eliminating all confounding and distorting factors (Bias and Confounder), so that different outcomes between the groups can be only explained by the intervention. There is a broad variation of quality of published RCTs. The reliability of results and extent to which findings provide a correct basis for generalisation to other circumstances needs to be validated. As part of a methods series of the Wiener Medizinische Wochenschrift this paper will discuss principles of study design, critical appraisal and limitations of RCTs.
Zusammenfassung
Die randomisiert kontrollierte Studie (engl. Randomised Controlled Trial, RCT) steht in der Hierarchie der Evidenz an der obersten Stufe aller Primärstudien, sie ist heute der Goldstandard, um den Effekt von Interventionen nachzuweisen. Das Studiendesign eines RCT besteht im Wesentlichen aus einer Interventions- und einer Kontrollgruppe, zu denen Patienten per Zufall zugeordnet werden. Nach Intervention bzw. Kontrollintervention wird das Auftreten vordefinierter Interventionsziele (Endpunkte) gemessen. Das Ziel des aufwändigen Studiendesigns ist es, alle störenden und verzerrenden Einflüsse auf die Studienendpunkte zu eliminieren, sodass ein gemessener Unterschied zwischen den Gruppen nur durch die Intervention erklärbar wird. Die methodische Qualität veröffentlichter RCTs ist sehr unterschiedlich. Um beurteilen zu können, in wieweit die Studienergebnisse einerseits die Realität abbilden und andererseits für die eigene Situation verwertbar sind, müssen Aspekte der internen und externen Validität der Studie betrachtet werden. Als Teil der Methoden Serie der Wiener Medizinischen Wochenschrift wird in diesem Artikel auf die Grundprinzipien von Studiendesign, kritischer Beurteilung und Limitationen von RCTs eingegangen.
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Mad, P., Felder-Puig, R. & Gartlehner, G. Randomisiert kontrollierte Studien. Wien Med Wochenschr 158, 234–239 (2008). https://doi.org/10.1007/s10354-008-0526-y
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DOI: https://doi.org/10.1007/s10354-008-0526-y