After 4 weeks , there were no significant between-group differences in cough-specific quality of life improvement ( montelukast : 52 , 45-59 ; placebo : 59 , 51-67 ; mean difference -05 , -15 to 06 , p = 038 ) or adverse event rates ( 21 ( 15 % ) of 137 patients on montelukast reported one or more adverse events ; 31 ( 22 % ) of 139 on placebo ; p = 014 ) .