In the modified intention-to-treat analysis these proportions were 14.4 % in the control group , 13.7 % in the 6-month group ( adjusted difference from control , 0.4 percentage points ; 90 % CI , -4.7 to 5.6 ) , and 26.9 % in the 4-month group ( adjusted difference from control , 13.1 percentage points ; 90 % CI , 6.8 to 19.4 ) .