Compared with normal responders , sensitive and highly sensitive responders spent greater proportions of time over-anticoagulated in the first 90 days of treatment ( median 22 % , IQR 0-202 ; 84 % , 0-258 ; and 183 % , 0-326 ; ptrend < 00001 ) and had increased risks of bleeding with warfarin ( sensitive responders hazard ratio 131 , 95 % CI 105-164 , p = 00179 ; highly sensitive responders 266 , 169-419 , p < 00001 ) .