Methodology of the Field Administration of Stroke Therapy - Magnesium (FAST-MAG) phase 3 trial: Part 2 - prehospital study methods

Int J Stroke. 2014 Feb;9(2):220-5. doi: 10.1111/ijs.12242.


Rationale: In acute stroke, the volume of salvageable brain tissue is maximal at onset and declines rapidly with time. Prehospital start of clinical trial interventions would enable delivery of neuroprotective agents, such as magnesium sulfate, to stroke patients in the hyperacute period when they are potentially most effective.

Aims: A broad aim of the FAST-MAG study is to develop and validate techniques to perform pivotal trials of neuroprotective therapies for acute stroke in the prehospital setting. In tandem with an accompanying general trial design article, this manuscript provides a detailed overview of several novel prehospital study methods employed in the NIH FAST-MAG Trial.

Design: Multicenter, randomized, double-blinded, placebo-controlled, pivotal clinical trial. Special Prehospital Procedures Distinctive prehospital methods deployed in FAST-MAG include: identifying likely stroke patients using the Los Angeles Prehospital Stroke Screen; eliciting explicit informed consent from patients or on scene legally authorized representatives via cellphone discussion with off-scene physicians; paramedic rating of pretreatment stroke severity using the Los Angeles Motor Scale; assigning patients to a study arm using blinded, pre-encounter randomization; facilitating continuity of study infusion from the field to the ED by stocking ambulances with study kits including both field and hospital doses; and electronic fax consent signature documentation by geographically separated subjects and enrolling physicians.

Discussion: The suite of prehospital trial methods developed for the FAST-MAG Trial enable enrollment of patients in very early time windows, including the hyperacute, 'golden hour' period immediately after stroke onset.

Keywords: ambulance; clinical trial; magnesium; neuroprotection; paramedic; prehospital.

Publication types

  • Clinical Trial, Phase III
  • Multicenter Study
  • Randomized Controlled Trial

MeSH terms

  • Double-Blind Method
  • Emergency Medical Services*
  • Female
  • Humans
  • Magnesium / therapeutic use*
  • Male
  • Neuroprotective Agents / therapeutic use*
  • Stroke / drug therapy*
  • Time Factors
  • Treatment Outcome


  • Neuroprotective Agents
  • Magnesium