Effect of waivers of consent on recruitment in acute stroke trials: A systematic review

Neurology. 2016 Apr 19;86(16):1543-51. doi: 10.1212/WNL.0000000000002587. Epub 2016 Mar 23.


There is urgent need for clinical trials of novel interventions to reduce the burden of acute ischemic stroke. A key impediment to such trials is slow recruitment. Since obtaining written informed consent in the setting of acute stroke is especially challenging, some experts have endorsed relaxing the requirement for informed consent by permitting verbal consent or waivers to facilitate recruitment. This systematic review of 36 randomized controlled trials of acute interventions for ischemic stroke assesses whether alternatives to written informed consent are associated with increased recruitment rates. After the exclusion of 2 outlier trials that differed from other trials in conduct and interventions studied, no association was observed on univariable analysis (8.9 participants/month in trials requiring written consent vs 6.1 participants/month in trials with alternatives, p = 0.43) or multivariable analysis (when adjusting for the number of centers, number of countries, and exclusions based on modified Rankin Scale scores). Alternatives to written informed consent in acute stroke trials may enable trial designs that would not be feasible otherwise. However, we did not find evidence that, within traditional trial designs, such alternatives are associated with faster recruitment.

Publication types

  • Review
  • Systematic Review

MeSH terms

  • Humans
  • Informed Consent*
  • Patient Selection*
  • Randomized Controlled Trials as Topic / methods*
  • Stroke* / therapy