Risk factors and outcomes of post-transplant erythrocytosis among adult kidney transplant recipients: a systematic review and meta-analysis.

Post-transplant erythrocytosis (PTE) can occur in up to 10-16% after kidney transplant (KT). However, the post-transplant outcomes of recipients with PTE in the literature were conflicting. We performed systematic review and meta-analysis of published studies to evaluate risk factors of PTE as well as outcomes of recipients who developed PTE compared with controls. A literature search was conducted evaluating all literature from existence through February 2, 2021, using MEDLINE and EMBASE. Data from each study were combined using the random-effects model. (PROSPERO: CRD42021230377). Thirty-nine studies from July 1982 to January 2021 were included (7,099 KT recipients). The following factors were associated with PTE development: male gender (pooled RR = 1.62 [1.38, 1.91], I2  = 39%), deceased-donor KT (pooled RR = 1.18 [1.03, 1.35], I2  = 32%), history of smoking (pooled RR = 1.36 [1.11, 1.67], I2  = 13%), underlying polycystic kidney disease (PKD) (pooled RR=1.56 [1.21, 2.01], I2 =44%), and pretransplant dialysis (pooled RR=1.6 [1.02, 2.51], I2 =46%). However, PTE was not associated with outcomes of interest, including overall mortality, death-censored graft failure, and thromboembolism. Our meta-analysis demonstrates that male gender, deceased-donor KT, history of smoking, underlying PKD, and pretransplant dialysis were significantly associated with developing PTE. However, with proper management, PTE has no impact on prognosis of KT patients.