INR of 2.0 had been achieved by day 5 for 13 % in the maintenance-dose group and for 50 % in the loading-dose group ( relative risk [ RR ] 0.27 , 95 % confidence interval [ CI ] 0.10-0 .60 ) and by day 10 for 68 % and 87 % , respectively ( RR 0.78 , 95 % CI 0.65-1 .00 ) .