Pure red cell aplasia with anti-erythropoietin antibodies occurs more commonly with one formulation of epoetin alfa than another.

Objective: To compare rates of pure red cell aplasia (PRCA) over time in patients with chronic renal failure treated with subcutaneous injections of two brands of epoetin alfa (either Eprex or Epogen) or epoetin beta (NeoRecormon).

Methods: Cases of antibody-mediated PRCA associated with epoetin alfa-treated patients were obtained from public databases and company websites and limited to time periods when exposure data also were available The subcutaneous exposure rates per 100 000 patient-years were calculated for the periods 1989-1998 and 1999-2002.

Results: The event rate for antibody-mediated PRCA for Epogen and Eprex were similar from 1989 to 1998, but the number of cases of Eprex-associated PRCA has increased markedly since 1999, even after accounting for subcutaneous exposure. In contrast, rates have remained low for Epogen and NeoRecormon.

Conclusions: The recent increase in PRCA appears to be product specific and cannot be explained solely as a consequence of increased use of the subcutaneous route of administration.