Providence, patient or provider? Looking for truth in retrospective database studies

Coulson, Tim G; Karalapillai, Dharshi

doi:10.1111/anae.14573

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…Some may also argue such conclusions should be used only to generate, revise and inform hypotheses, and should not be used to demonstrate causality. In that sense, there are many parallels to be drawn with observational database studies .…”

Section: Data Recyclingmentioning

confidence: 99%

Recycling old data – an ethical and pragmatic way to generate new evidence?

Charlesworth

Agarwal

2019

Anaesthesia

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In this issue of Anaesthesia, Ho et al. report data suggesting that, for cardiac surgical patients, platelet dysfunction towards the end of cardiopulmonary bypass is associated with adverse postoperative outcomes [1].Following corrections for several confounders, they conclude a 1% increase in platelet dysfunction was associated with a 1% increase in the odds of a composite outcome of adverse events. Before we consider the clinical implications of this finding, there are two important aspects of their paper that warrant further discussion. These relate to the stepped-wedge cluster randomised controlled trial from which the authors retrieved data to test their hypothesis [2] and the recycling of old datasets to answer new research questions. Stepped-wedge cluster randomised controlled trialsThere is already good evidence that patient blood management strategies reduce peri-operative allogeneic blood transfusions and are associated with better postoperative outcomes for patients undergoing all types of major surgery [3,4]. It also seems reasonable that access to intra-operative point-of-care tests of coagulation in combination with integrated transfusion algorithms may reduce the need for allogeneic blood transfusion. That said, before the study by Karkouti et al. [2], the evidence for such strategies was limited to observational, non-controlled studies. In order to build a case for the purchasing of equipment, hospitals, departments, policymakers and clinical managers may ask for randomised controlled trial evidence. There are nevertheless several logistical barriers to a conventional trial such as, but not limited to, the complexity of 'rolling out' the intervention at different timepoints for different patients at different centres. When the intervention is a complex package of care, such as those commonly employed in large multi-centre quality improvement projects [5,6], the stepped-wedge design allows for randomisation of clusters at different time-points ( Fig. 1).In stepped-wedge cluster trials, observations are first made during a baseline period when all clusters are controls, and no participant receives the intervention.Clusters then cross over from the control arm to the intervention arm, but at different time-points. As the study progresses, increasing numbers of clusters cross over to the intervention arm so that by the end of the study, all participants in all clusters are receiving the intervention. As this occurs, data are continually collected post-intervention.The name 'stepped wedge' comes from the stepped wedge shape in Fig. 1.The design of such studies is complicated by many factors, including: the need to determine the number of clusters; the length of each step; the number of clusters randomised at each step and how best to power such

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Section: Data Recyclingmentioning

confidence: 99%

Recycling old data – an ethical and pragmatic way to generate new evidence?

Charlesworth

Agarwal

2019

Anaesthesia

View full text Add to dashboard Cite

show abstract

“…The suggestion that postoperative pulmonary complications can be prevented through selecting one mode of mechanical ventilation over another – although it may seem neat, simple and plausible – is probably incorrect. Even with the best intentions, one cannot entirely discount the possibility of unmeasured confounders leading to a non‐causal association in large retrospective database studies .…”

mentioning

confidence: 99%