Upon arrival to the ED , the GCS was 20 % lower ( 7.8 ( SD = 5.3 ) vs 9.7 ( SD = 6.3 ) ) and the RTS was 12 % lower ( 5.3 ( SD = 2.0 ) vs 6.0 ( SD = 2.1 ) ) than EMS values in blunt trauma patients ( P < .001 ) .