Anemia after kidney transplantation; its prevalence, risk factors, and independent association with graft and patient survival: a time-varying analysis.

INTRODUCTION: Posttransplant anemia and its association with transplant outcomes have not been properly studied.

METHODS: We examined 530 renal allograft recipients transplanted at our center and followed up for 31.0±14.1 months. Hemoglobin (Hb), serum bicarbonate, and creatinine; use of erythropoiesis-stimulating agent (ESA) and iron; and immunosuppressive regimen data were obtained at multiple time points during 24-month posttransplant.

RESULTS: The overall prevalence of anemia was 89.4% at the time of transplant, dropping to 49.2% at 1 year and 44.3% at 2 years. ESA use decreased from 25.6% at 1 month to 8.23% at 24 months, only in 30.9% to 51.2% with severe anemia; 21.0% to 29.2% received iron supplements. Factors independently predictive of Hb included male gender (β=0.64, P<0.001, confidence interval [CI]: 0.45-0.82), estimated glomerular filtration rate (β=0.21 per 10 mL/min/1.73 m, P<0.001; CI: 0.16-0.27), bicarbonate (β=0.4 per 10 mmol/L increase, P<0.001; CI: 0.31-0.85), using angiotensin-converting enzyme inhibitor/angiotensin receptor blocker (β=0.36, P<0.001; CI: 0.16-0.55), African American race (β=-0.34, P=0.001, CI:-0.54 to -0.14), iron (β=-0.28, P=0.003, CI:-0.47 to -0.09) and ESA use (β=-0.73, P<0.001, CI:-0.93 to -0.52), and prednisone (β=-0.46, P<0.001, CI:-0.71 to -0.22 for >10 mg/day vs. none). Using a competing-risk regression model, Hb less than 9 in men and less than 8 in women, was associated with 5.25-fold higher risk of death-censored graft loss compared with no anemia (adjusted, P=0.005, CI: 1.7-16.7). Degree of anemia also remained significantly associated with risk of death (hazard ratio [HR]: 2.2, P<0.1, CI: 0.9-5.6 for grade 2; HR: 3.9, P=0.009, CI: 1.4-10.8 for grade 3; and HR: 4.8, P=0.08, CI: 1.5-15.4 for grade 4, all vs. grade 0).

CONCLUSION: We showed that posttransplant anemia is common, and ESA/iron use remains suboptimal, and Hb is independently associated with graft failure and mortality.