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The price of certainty: when is a new therapy good enough?
  1. Jens Fiehler1,
  2. Kamil Zeleňák2,
  3. Antonia Zapf3
  1. 1 Department of Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
  2. 2 Department of Radiology, Comenius University in Bratislava Jessenius Faculty of Medicine in Martin Clinic of Radiology, Martin, Slovakia
  3. 3 Department of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
  1. Correspondence to Dr Jens Fiehler, Department of Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; fiehler{at}

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“Our aim as scientists is objective truth; more truth, more interesting truth, more intelligible truth. We cannot reasonably aim at certainty.” Karl Popper (from In Search of a Better World, 1995).

The enormous success of endovascular thrombectomy (EVT) for stroke treatment has engendered increasing interest from the medical scientific community as well as industry. New companies have been founded and substantial capital raised and used for the development of new technologies to further improve patient outcomes in ischemic stroke and in other conditions in the neurointerventional realm. These new technologies need to be developed and subsequently tested for their performance and safety in patient care. Prospective single-arm studies are a reasonable standard for the early phase of a device evaluation. For such studies, the comparator and its point estimate are typically based on a meta-analysis of historical data. Other study designs such as virtual comparator groups have been tested as well.1 Recently, more randomized controlled trials (RCTs) have been initiated relatively early following encouraging observations in multiple case series. The numerous RCTs that were started in the field of middle meningeal artery embolization are positive examples of this.2–5 This development indicates a trend towards better neurointerventional study quality that is also observed in RCTs whose purpose is the head-to-head comparison of different devices.6

There are two common hypothesis scenarios for testing the primary efficacy endpoint (eg, clinical outcome after 3 months). First, testing for superiority regarding efficacy is chosen if the new therapy has the potential to be more costly or risky. Second, testing for non-inferiority is conducted if the new therapy is comparable to the previous standard therapy but might offer advantages in other areas …

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  • Contributors All authors contributed equally.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.