Multivariate logistic regression analysis showed that activation of the variable stiffness function regularly ( odds ratio [ OR ] , 0.53 ; 95 % confidence interval [ CI ] , 0.28 , 0.98 ; p = 0.04 ) or on an as-needed basis ( OR , 0.52 ; 95 % CI , 0.28 , 0.97 ; p = 0.04 ) were independent factors that were related with less use of abdominal pressure .
