Pregabalin increased POD1 drowsiness ( 34.5 , 37.9 , 55.2 , and 58.6 % in the 0 , 50 , 100 , and 150 mg arms , respectively ; P = 0.030 ) , but did not increase confusion ( 0 , 3.5 , 0 , and 3.5 % , respectively ; P = 0.75 ) .