Posttransplant lymphoproliferative disorder among renal transplant patients in relation to the use of mycophenolate mofetil

BACKGROUND: The introduction of increasingly effective immunosuppressants has raised the question of whether posttransplant lymphoproliferative disorder (PTLD), a complication of immunosuppression, would become more frequent. This study assessed the risk of PTLD in relation to immunosuppression during a period that saw the introduction and eventual market dominance of mycophenolate mofetil (MMF). METHODS: A case-control study was conducted at 23 U.S. transplant centers. All participants received a renal-only transplant on or after July 1, 1995. PTLD cases were reported by centers and confirmed by central review. The United Network for Organ Sharing (UNOS) supplemented case ascertainment and identified controls matched on center, transplant date, and age. Center personnel abstracted risk factor and therapy data for cases and up to four controls per case. Cases and controls were compared, using a matched multivariate analysis, to assess the impact of MMF as one component of triple-therapy adjusted for other drug therapies and known risk factors. RESULTS: Data were collected for 108 PTLD cases and 404 controls. PTLD risk for individuals on triple therapy with MMF was similar to the risk experienced by individuals on triple therapy with no MMF (adjusted odds ratio=1.19; 95% CI 0.55-2.55). There was no dose response relationship between MMF and PTLD risk. CONCLUSIONS: Use of MMF was not associated with an increase in PTLD among patients who received triple immunosuppressive therapy, but an excess in risk as large as 155% or a reduction in risk by as much as 45% cannot be ruled out.