The rates of death and/or severe neurodevelopmental impairment for the B/A ratio versus TSB groups were 15.4 % versus 15.5 % ( P = 1.0 ) and 2.8 % versus 1.4 % ( P = 0.62 ) for birth weights 1000 g and 1.8 % versus 5.8 % ( P = 0.03 ) and 4.1 % versus 2.0 % ( P = 0.26 ) for birth weights of > 1000 g.