Post-transplant erythrocytosis: a disappearing phenomenon?

BACKGROUND: Erythrocytosis is relatively common post-kidney transplantation and may have adverse consequences. This study examined whether the incidence of erythrocytosis has remained stable over time and explored the impact of this condition on patient outcomes.
METHODS: This was a retrospective single center review of an incidence cohort (transplanted between 1993 and 2005). Predictors of erythrocytosis and hemoglobin levels and subsequent patient and allograft survival were examined.
RESULTS: Erythrocytosis (hemoglobin >170 g/L for >1 month) was observed in 59 of 511 recipients. Erythrocytosis developed in only 8.1% of those transplanted from 1997 to 2005, compared with 18.7% in those transplanted from 1993 to 1996 (p = 0.0005). Independent predictive factors were use of angiotensin converting enzyme inhibitors/angiotensin receptor blockers (ACEi/ARBs) (HR 0.176, 95% CI 0.040-0.71, p = 0.016), male gender (HR 3.72, 95% CI 1.54-9.0, p = 0.003), and mycophenolic acid agents (HR 0.49, 95% CI 0.237-0.99, p = 0.049). Patients with erythrocytosis had superior overall survival (HR for death 0.105, 95% CI 0.014-0.760, p = 0.026) but a trend for worse death censored graft loss (univariate HR 2.06, 95% CI 0.91-4.65, p = 0.084).
CONCLUSIONS: The incidence of erythrocytosis is falling and is likely related to greater ACEi/ARB use and possibly more antiproliferative immunosuppression. Patient survival is excellent in those with erythrocytosis, but long-term graft survival may be compromised.