Impact of post‐transplant anemia on patient and graft survival rates after kidney transplantation: a meta‐analysis

The impact of post-kidney transplant anemia (PTA) on patient and graft survival rates remains controversial. We performed a meta-analysis to evaluate its impact in causing death of a patient with a functioning graft (DPWFG) and death-censored graft loss (DCGL). A systematic review of 11 observational studies (11,632 kidney transplant patients) that reported the impact of PTA or hemoglobin (Hb) level on these endpoints was performed. Using the World Health Organization (WHO) definition (Hb <12 g/dL in women and Hb <13 g/dL in men), PTA was not associated with DPWFG when results were expressed as an adjusted hazard ratio (aHR: 1.23 [0.97-1.57]), but was associated with higher DPWFG when results were expressed as unadjusted rates (aHR: 2.48 [1.36-4.52]) and when cut-off level for anemia was lower than the WHO definition (aHR: 3.12 [1.92-5.07]). A -1 g/dL decrease in Hb level was associated with higher DPWFG rates (aHR: 1.19 [1.12-1.26]). Using WHO criteria, PTA was associated with higher DCGL rates when results were expressed as aHR (aHR: 1.53 [1.26-1.85]) or as unadjusted rates (aHR: 3.55 [2.36-5.33]); a -1 g/dL decrease in Hb level was associated with higher DCGL rates (aHR: 1.14 [1.11-1.16]). This meta-analysis reveals that the association between PTA and DPWFG varies with PTA definition and adjustment for confounders. In all sub-meta-analyses, PTA was significantly associated with DCGL.