We conducted a double-blind , multicenter clinical trial in which patients with severe , moderate-to-severe , or moderate acute TBI ( Glasgow Coma Scale score of 4 to 12 , on a scale from 3 to 15 , with lower scores indicating a lower level of consciousness ) were randomly assigned to intravenous progesterone or placebo , with the study treatment initiated within 4 hours after injury and administered for a total of 96 hours .