The primary outcome was treatment failure ( composite outcome of early treatment failure defined as [ 1 ] clinical deterioration indicated by development of shock , [ 2 ] need for invasive mechanical ventilation not present at baseline , or [ 3 ] death within 72 hours of treatment ; or composite outcome of late treatment failure defined as [ 1 ] radiographic progression , [ 2 ] persistence of severe respiratory failure , [ 3 ] development of shock , [ 4 ] need for invasive mechanical ventilation not present at baseline , or [ 5 ] death between 72 hours and 120 hours after treatment initiation ; or both early and late treatment failure ) .