Diagnoses for medical conditions within Medicare data come from claims submitted by providers for the fee-for-service sections of Medicare, Part A (hospital care) and Part B (ambulatory care). We restricted our analysis sample to beneficiaries aged 65 years or older who have Parts A and B coverage for the entire calendar year and had at least 1 outpatient visit in the calendar year. Between 20% and 25% of beneficiaries each year used Part C, managed care/Medicare Advantage plans, and are excluded because their care was paid on a capitated basis and claims with diagnoses are not available.

Data are from the Medicare 5% Sample Limited Data Sets (LDS) for Inpatient, Outpatient, and Carrier (formerly known as Physician/Supplier Part B file) claims. For this indicator, patients were identified as having ESRD through the ESRD Indicator provided on the Denominator file and not counted as having a CKD diagnosis. See the Field/Data tab for the list of ICD-9-CM or ICD-10-CM used to determine CKD.