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Most U.S. Neurovascular Trials Disrupted by COVID-19 Pandemic

Key findings

  • 101 U.S. clinical trial sites were invited to respond to an online survey about the effects of COVID-19 on research into endovascular treatment of acute ischemic stroke and cerebral aneurysm
  • Most sites either partially (46%) or completely (32%) suspended trial enrollment between the middle and end of March 2020
  • Neuroendovascular trial quality was compromised: many sites reported missed clinical (42%) and imaging (37%) follow-up milestones, and 42% of sites reported protocol deviations due to the pandemic
  • On the other hand, the pandemic has revealed opportunities to improve clinical trial infrastructure including increased use of virtual access for consent and follow-up

As the COVID-19 pandemic continues, clinical trial investigators are facing protocol deviations, trial modifications and challenges in patient monitoring. Faced with these problems themselves, Thabele Leslie-Mazwi, MD, director of Neuroendovascular Stroke Services and a specialist in the Division of Neurocritical Care in the Department of Neurology and Department of Neurosurgery at Massachusetts General Hospital, and colleagues surveyed U.S. centers to explore the effect of the COVID-19 pandemic on research into the endovascular treatment of acute ischemic stroke and cerebral aneurysms.

In the Journal of NeuroInterventional Surgery, the team discusses several ways physicians can improve their ability to carry on clinical research during the pandemic.

Study Details

The 19-question survey was written by four neuroradiologists, five neurosurgeons and three neurologists, each with 10 or more years of experience in clinical practice. All were site principal investigators and six were leading clinical trials as national principal investigators.

To assemble the survey sample, writing group members used to identify relevant U.S. trials and affiliated investigators. In addition, they asked sponsors and principal investigators of ongoing trials to provide lists of participating sites. The online survey was distributed to 101 sites by email and was open from April 21 to May 21, 2020. Surveys were completed voluntarily by a research coordinator, with each center permitted only one response.

Trial Suspension

Sixty-five trial sites responded:

  • Most either partially (46%) or completely (32%) suspended trial enrollment between the middle and end of March 2020
  • 75% placed new trials on hold (between 1 and 7 postponed trials per site)

Effects on Ongoing Trials

  • 42% of sites missed clinical follow-up visits
  • 37% missed imaging follow-up
  • 42% reported protocol deviations (e.g., delayed reporting of events)
  • 26% experienced delay/loss of reimbursements
  • Two sites reported a diagnosis of COVID-19 among enrolled patients


  • 94% of sites developed alternative mechanisms such as telemedicine for trial follow-up visits
  • 52% of sites allow electronic or telephone consent for enrollment for some studies and 8% allow remote consent for all studies

Coping with Continued Disruption

These findings suggest several opportunities to update the conduct of clinical trials during this pandemic and beyond. They include:

  • Deciding how to handle prospective trial participants regarding COVID-19 exposure
  • Developing protocols for remote consent: harness virtual technologies that allow for face-to-face interactions with legally authorized representatives, the electronic exchange of documents and digital signatures
  • Reducing reliance on in-person patient monitoring
  • Considering increasing focus on adaptive trial designs (such as platform trials) since flexibility and responsiveness are key advantages at this time

Although the study focuses on neurovascular research, the results may be generalizable to U.S. clinical trials in other medical specialties.

partially or completely suspended trial enrollment because of COVID-19

placed new trials on hold because of COVID-19

reported protocol deviations because of COVID-19

allow electronic or phone consent for enrollment for some or all studies because of COVID-19

Learn more about the Division of Vascular and Endovascular Surgery

Refer a patient to the Department of Neurosurgery


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