In the ITT analyses , participants showed significant improvement in bowel symptoms as measured by the PAC-SYM ( mean SD , -0.28 0.60 , range : -1 -2.33 ) and PAC-QOL ( mean SD , 0.33 0.81 , range : -1.5 -2.0 ) over time , but there were no significant differences between the lubiprostone and Senna groups in mean change in the PAC-SYM ( -0.20 0.60 vs -0.36 0.61 , P = 0.61 respectively ) or the PAC-QOL ( 0.29 0.76 vs 0.37 0.87 , P = 0.61 respectively ) .