A Study of Patients With Pure Red Cell Aplasia Associated With Recombinant Human Erythropoietin Treatment

• Number of participants with Pure Red Cell Aplasia (PRCA) outcome (Initial observation phase) [ Time Frame: Up to 24 months after the date of loss of efficacy ] [ Designated as safety issue: No ]
  The PRCA outcome is measured by anti-epoetin alfa qualitative test. Persistence of PRCA is defined as: 1) absolute reticulocyte count less than 30,000 per cubic millimeter; and/or 2) no reversal of erythroblastopenia on repeated bone marrow testing. Resolution of PRCA is defined as: 1) absolute reticulocyte count greater than or equal to 30,000 per cubic millimeter; and/or 2) reversal of erythroblastopenia on repeated bone marrow testing.
  
  
• Number of participants with pure red cell aplasia outcome (Extended observation phase) [ Time Frame: Up to 2 years after the enrollment in the extended observation phase ] [ Designated as safety issue: No ]
  Participants remaining anti-epoetin alfa positive 24 months after loss of efficacy will enter in the extended observation period.
  
  
• Overall clinical outcome of pure red cell aplasia (Initial observation phase) [ Time Frame: Up to 24 months after the date of loss of efficacy ] [ Designated as safety issue: No ]
  The overall clinical outcome is evaluated by anti-epoetin alfa qualitative test. Overall clinical status will be recorded at each visit in the initial and extended observation phases using a categorical scale (improved, same, worsened, death). In case of death, the date and cause of death along with the the date and cause of death will be recorded.
  
  
• Overall clinical outcome of pure red cell aplasia (Extended observation phase) [ Time Frame: Up to 2 years after the enrollment in the extended observation phase ] [ Designated as safety issue: No ]
  

• Different treatment modalities with pure red cell aplasia outcome (Initial observation phase) [ Time Frame: Up to 24 months after the date of loss of efficacy ] [ Designated as safety issue: No ]
  
• Different treatment modalities with pure red cell aplasia outcome (Extended observation phase) [ Time Frame: Up to 2 years after the enrollment in the extended observation phase ] [ Designated as safety issue: No ]
  
• Risk factors for Loss of Efficacy (LOE) and pure red cell aplasia (PRCA) outcome [ Time Frame: Period between LOE date and date of enrollment in the study ] [ Designated as safety issue: No ]
  This data will be collected retrospectively and the date of LOE will be determined by the sponsor based upon reported data. PRCA duration groups will be summarized by potential risk factors to evaluate the relationship of risk factors to the duration of PRCA.
  
  

This is a multicenter (study conducted at multiple sites), observational (study in which the investigators/physicians observe the participant's data and measure their outcomes) study. Approximately 150 participants will be enrolled in this study. The study consists of an initial observation phase and extended observation period. An initial observation phase starting at enrollment and ending when 24 months have elapsed since the date of loss of efficacy (LOE), supplemented with retrospective data collection for the period between LOE date and date of enrollment in the study. Participants remaining epoetin alfa (EPO-Ab) positive 24 months after LOE will enter a 2-year extended observation period. Study visits will take place every month during the initial observation phase and data will be collected every 6 months during the extended observation phase. Safety evaluations will include assessment of adverse events, clinical laboratory tests, vital signs, and physical examination which will be monitored throughout the study. The total study duration for each participant will be approximately for 4 years.