FIGURE 1:

Study population selection from the USRDS. We selected a contemporary cohort of patients 67 years of age or older with no history of warfarin use in the past year whose primary payer was Medicare who initiated renal replacement therapy between 1 January 2007 and 31 December 2008 and underwent HD at a participating facility on Day 90 (±10 days; index date) after their first ESRD service date.