Should prophylaxis for Pneumocystis carinii pneumonia in solid organ transplant recipients ever be discontinued?

Solid organ transplant recipients are at risk for Pneumocystis carinii pneumonia (PCP), but the risk of PCP beyond 1 year is poorly defined. We identified 25 cases of PCP in 1,299 patients undergoing solid organ transplantation between 1987 and 1996 at The Cleveland Clinic Foundation (4.8 cases per 1,000 person transplant-years [PTY]). Ten (36%) of 28 PCP cases (transplantation was performed before 1987 in three cases) occurred > or = 1 year after transplantation, and no patient developed PCP while receiving prophylaxis for PCP. The incidence of PCP during the first year following transplantation was eight times higher than that during subsequent years. The highest rate occurred among lung transplant recipients (22 cases per 1,000 PTY), for whom the incidence did not decline beyond the first year of transplantation. We conclude that the incidence of PCP is highest during the first year after transplantation and differs by type of solid organ transplant. Extending the duration of PCP prophylaxis beyond 1 year may be warranted for lung transplant recipients.