The hazard ratio for death at 90 days was 2.01 ( 95 % confidence interval [ CI ] , 1.01 to 3.99 ) with standard oxygen versus high-flow oxygen ( P = 0.046 ) and 2.50 ( 95 % CI , 1.31 to 4.78 ) with noninvasive ventilation versus high-flow oxygen ( P = 0.006 ) .