Why don't multicenter randomized controlled trials (RCT) confirm the positive findings of single center RCTs in acute care? (Zeno's Paradox of the Tortoise and Achilles revisited).

Why don't multicenter randomized controlled trials (RCT) confirm the positive findings of single center RCTs in acute care? (Zeno's Paradox of the Tortoise and Achilles revisited).
Minerva Anestesiol. 2018 Oct 30;:
Authors: Landoni G, Pieri M, Young PJ, Bellomo R
Abstract
It is a common observation that many multicenter randomized controlled trials (mRCT) performed in critically ill patients do not achieve the positive findings often seen in single centre studies (sRCT). This has, of course, relevant consequences for clinical practice, as mRCTs have higher scientific validity compared to sRCTs. The aim of this manuscript was to review and discuss the several potential causes of this phenomenon and to relate them to the future of mRCTs in critical care medicine. Overall, this seems to recall the old mythologic story of Achilles and the tortoise: although mRCTs (i.e. Achilles) are much more powerful, indeed, they always arrive later in time compared to the sRCTs (i.e. the tortoise) from which they were powered. However, sRCTs are more prone to several bias compared to mRCTs, such as local effect bias, selection and performance bias, detection and reporting bias, analysis and attrition bias, concomitant therapy bias, low fragility index and publication bias. In this sense, it is high time the critical care community should see the positive findings of sRTCs with a very high level of scientific caution, unless they are confirmed by mRCTs...

Source: Minerva Anestesiologica - November 6, 2018 Category: Anesthesiology Tags: Minerva Anestesiol Source Type: research