This study consists of two phases. The purpose of phase 1 is to identify incidence and patterns of erythropoiesis-stimulating agent (ESA) hyporesponsiveness and its associated factors in ESA treated patients. The purpose of phase 2 to identify outcomes associated with ESA hyporesponsiveness. Key aspects of the phase 2 study design will entirely depend on the results from phase 1.

This is a retrospective database analysis of patients with anemia associated with chronic kidney disease (CKD) treated with ESAs from January 1st 2015 - December 31st 2021. Data will be derived from European Clinical Database (EuCliD).

Inclusion Criteria:

All patients

• Patient has a diagnosis of chronic kidney disease valid between January 1st, 2015, and December 31st, 2021 and is documented in the EuCliD database (incident and prevalent patients)
• Patient who is treated with renal replacement therapy (RRT) (CKD Stage 5) during the study period
• Patient receiving erythropoiesis-stimulating agent (ESA) therapy, within the data collection period having EuCliD data available for a period of the previous 30 days before Index Date but not strictly limited to patients that enter the study period as ESA naïve patients
• Patient having provided consent for secondary use of their data for research purposes
• Patient has a known ESA administration route (intravenous/subcutaneous)
• Patient with a hemoglobin value available at baseline (+/- 20 days allowed) and at least one valid hemoglobin value afterwards
• Patient having at least one body weight value available

Hyporesponsive Cohort

• Patients meeting the hyporesponsive criteria on at least one occasion. The criteria for ESA hyporesponsive will follow the National Institute for Health and Care Excellence, UK (NICE) guidelines:

  • for epoetin alfa, 300 IU/kg/week or more of subcutaneous epoetin or 450 IU/kg/week or more of intravenous epoetin
  • for darbepoetin, dose ≥ 1.5 μg/kg per week

Responsive Cohort

• Patients with all ESA doses lower than those defined by the hyporesponsive criteria

Exclusion Criteria:

• Patient with evidence of hereditary hemolytic anemia (International Classification of Diseases 10th Revision [ICD-10] code D58.9)
• Patient receiving transplant within 6 months prior to Index Date

The study population will be patients with anemia of CKD treated with ESA in stage 5D, i.e., on renal replacement therapy (RRT), including extracorporeal RRT and peritoneal dialysis (PD) prevalent as patients in Fresenius Medical Care (FME)'s Nephrocare centers and documented in the EuCliD data base between January 1st 2015 and December 31st 2021.

Access to anonymized individual participant level data will not be provided for this trial. Further details on Astellas' data sharing policy can be found at https://www.clinicaltrials.astellas.com/transparency/.