The median duration of antibiotic therapy was 4.0 days ( interquartile range , 4.0 to 5.0 ) in the experimental group , as compared with 8.0 days ( interquartile range , 5.0 to 10.0 ) in the control group ( absolute difference , -4.0 days ; 95 % CI , -4.7 to -3.3 ; P < 0.001 ) .