Data Sources

The US Renal Data System (USRDS) ESRD database was used for this study. The USRDS ESRD database consists of data from the ESRD Medical Evidence Report, the ESRD Death Notification form, and Medicare Parts A and B claims. From Medicare, which insures the majority of patients who receive maintenance dialysis, we used billing claims data to determine the presence of comorbid conditions, to derive the Liu comorbidity index,²⁷ and to generate a putative marker of morbidity based in part on claims for DME use (further described in the next section).