In normal pH subgroup , fluoxetine was superior to both omeprazole and placebo regarding percentage of heartburn-free days ( median improvement , 57.1 , IQR 35.7-57 .1 vs 13.9 , IQR , 0-45 .6 and 7.14 , 0-23 .8 , respectively , p < 0.001 ) , but no significant difference was observed between medications in abnormal pH subgroup .