While the authors consider an improvement of 16 or more to be clinically meaningful , the changes from baseline in mean SNOT-20 scores of those treated with irrigation ( and the differences with those treated with nasal spray ) at 2 , 4 , and 8 weeks were 12.2 ( difference 5.5 , [ 95 % confidence interval -0.04 to 11.0 ] ) , 16.2 ( difference 8.8 [ 3.2 to 14.4 ] ) , and 15.0 ( difference 6.5 [ 0.4 to 12.6 ] ) , respectively .