Open Access

Underpowered trials in critical care medicine: how to deal with them?

  • Bob Roozenbeek1, 2Email author,
  • Hester F Lingsma2,
  • Ewout W Steyerberg2,
  • Andrew IR Maas1 and
  • the IMPACT Study Group
Critical Care201014:423

https://doi.org/10.1186/cc9021

Published: 8 June 2010

In their recently published article, Dr Aberegg and colleagues described interesting results of a literature search for randomized controlled trials comparing mortality of therapies for critically ill adults in five high impact journals over a 10 year period [1]. The authors show that the predicted delta (the effect size of a therapy compared to control) used for power calculations was substantially larger than the observed delta in the majority of the included studies. They conclude that this finding, referred to as 'delta inflation', led to underpowered trials in the field of critical care medicine.

We agree that treatment effects are small in this field of medicine and that many critical care trials have been underpowered. This problem is particularly relevant to the field of neurocritical care after traumatic brain injury [2]. The IMPACT (International Mission on Prognosis and Clinical Trial Design in Traumatic Brain Injury) Study Group extensively investigated possible causes and solutions and recently reported recommendations for improving the design and analysis of future clinical trials in traumatic brain injury to increase statistical power [3]. These include the use of relatively broad enrolment criteria instead of strict patient selection [4], covariate adjustment for baseline patient characteristics [5], and ordinal rather than dichotomous outcome analysis [6]. In our opinion these recommendations are also applicable to other fields of critical care research characterized by heterogeneous patient populations. We submit that adopting these recommendations in future trials will increase the chance of detecting small but clinically relevant treatment effects in critical care medicine.

Declarations

Authors’ Affiliations

(1)
Department of Neurosurgery, Antwerp University Hospital
(2)
Department of Public Health, Antwerp University Hospital,Erasmus MC

References

  1. Aberegg SK, Richards DR, O'Brien JM: Delta inflation: a bias in the design of randomized controlled trials in critical care medicine. Crit Care 2010, 14: R77. 10.1186/cc8990PubMed CentralView ArticlePubMedGoogle Scholar
  2. Maas AI, Roozenbeek B, Manley GT: Clinical trials in traumatic brain injury: past experience and current developments. Neurotherapeutics 2010, 7: 115-126. 10.1016/j.nurt.2009.10.022View ArticlePubMedGoogle Scholar
  3. Maas AI, Steyerberg EW, Marmarou A, McHugh GS, Lingsma HF, Butcher I, Lu J, Weir J, Roozenbeek B, Murray GD: IMPACT recommendations for improving the design and analysis of clinical trials in moderate to severe traumatic brain injury. Neurotherapeutics 2010, 7: 127-134. 10.1016/j.nurt.2009.10.020View ArticlePubMedGoogle Scholar
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Copyright

© BioMed Central Ltd 2010

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