A Study of Risk Factors for Anti-erythropoietin Antibody Positive Pure Red Cell Aplasia Among Patients With Chronic Kidney Disease Receiving Epoetin Alfa

Primary Outcome Measures:

• Study medication-related risk factors: Number of participants who received Human Serum Albumin (HSA) containing drug [ Time Frame: 1 year prior to the reference date ]
  The reference date is the day on which Loss of Efficacy (LOE) was first suspected, where LOE is the date that a drop in hemoglobin of greater than 2 g/dL/month was first seen.
  
  
• Study medication-related risk factors: Number of participants who received HSA-free drug [ Time Frame: 1 year prior to the reference date ]
  
• Study medication administration-related risk factors: Number of participants who received epoetin alfa intravenously [ Time Frame: 1 year prior to the reference date ]
  
• Study medication administration-related risk factors: Number of participants who received epoetin alfa subcutaneously [ Time Frame: 1 year prior to the reference date ]
  
• Study medication administration-related risk factors: Number of participants who self-administered epoetin alfa [ Time Frame: 1 year prior to the reference date ]
  
• Study medication administration-related risk factors: Number of participants who administered epoetin alfa in hospital or in clinic [ Time Frame: 1 year prior to the reference date ]
  
• Study medication administration-related risk factors: Number of participants with the duration of epoetin alfa treatment [ Time Frame: 1 year prior to the reference date ]
  
• Study medication administration-related risk factors: Number of participants with the duration of other recombinant human erythropoietins (r-HuEPOs) treatment [ Time Frame: 1 year prior to the reference date ]
  
• Study medication administration-related risk factors: Number of participants with exposure to epoetin alfa [ Time Frame: 1 year prior to the reference date ]
  
• Study medication administration-related risk factors: Number of participants with exposure to other r-HuEPOs [ Time Frame: 1 year prior to the reference date ]
  
• Study medication administration-related risk factors: Number of participants with frequency of epoetin alfa dosing [ Time Frame: 6 months prior to the reference date ]
  
• Study medication administration-related risk factors: Number of participants with frequency of other r-HuEPOs dosing [ Time Frame: 6 months prior to the reference date ]
  
• Participant-related risk factors: Number of participants according to age [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants according to sex [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants according to race [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants according to underlying diagnosis of chronic kidney disease [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants according to type of renal replacement therapy (if any at the time of the reference date) [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with history of malnutrition [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with history of autoimmune disease or positive results of autoimmune testing [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with history of immune dysregulation [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with uncontrolled hyperparathyroidism [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with uncontrolled hypothyroidism [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with history of malignancy [ Time Frame: 5 years prior to the reference date ]
  
• Participant-related risk factors: Number of participants with history of viral infection [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with history of vaccination [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with immunosuppressive/immunomodulatory therapy [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with history of frequent transfusions [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with treatment with other subcutaneous medications [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants with treatment with other recombinant human proteins [ Time Frame: 1 year prior to the reference date ]
  
• Participant-related risk factors: Number of participants who received other concomitant therapy [ Time Frame: 1 year prior to the reference date ]
  

Secondary Outcome Measures:

• Human leukocyte antigen (HLA) typing [ Time Frame: 1 year prior to the reference date ]
  The optional pharmacogenomic (use of genetic information to predict whether the study medication will help make a patient well or ill) part of the study will test for polymorphisms and haploid types of the erythropoietin gene. HLA typing will be recorded for the control participants who will sign the pharmacogenomics part of the study.
  
  

This is a multicenter (study conducted at multiple sites), case-control (study that compare individuals with a disease or condition [cases] to a group of individuals without the disease or condition [controls] to determine the possible factor which increased disease incidence), retrospective (a study in which the participants are identified and then followed backward, as time passes) study. Retrospective risk factor data will be collected for control participants matched to the subset of participants in Protocol EPO-IMU-301 identified as having chronic kidney disease and anti-EPO antibody positive PRCA that began while the participant was receiving treatment with EPREX (index participants). For each index participant, up to 4 matched non-PRCA control participants with chronic kidney disease will be enrolled in this study. Approximately 600 control participants will be enrolled in this study. Control participants will be selected from the same site as the index participant and the data will be collected from the date closest to the reference date (loss of efficacy [drop in hemoglobin of greater than 2 g/dL/month] was first seen) that the control participant satisfies all study inclusion and exclusion criteria. The optional pharmacogenomic part (testing for polymorphisms and haploid types of the erythropoietin gene) will be recorded for the control participants who will sign the pharmacogenomics part of the study. No drug administration or treatment will be mandated by this study. Safety evaluation will include assessment of adverse events.