After 12 months , the mean blood pressure had decreased to 128.2 / 73.8 mm Hg in the intervention group and to 137.8 / 76.3 mm Hg in the control group , a difference of 9.2 mm Hg ( 95 % CI , 5.7-12 .7 ) in systolic and 3.4 mm Hg ( 95 % CI , 1.8-5 .0 ) in diastolic blood pressure following correction for baseline blood pressure .