The difference between the United States/Canada versus Eastern Europe/Russia persisted after adjustment for key prognostic variables : adjusted hazard ratios 1.34 ( 95 % confidence interval , 1.01-1 .74 ; P = 0.04 ) in I-Preserve and 1.85 ( 95 % confidence interval , 1.17-2 .91 ; P = 0.01 ) in CHARM-Preserved .