Anemia at 1 year after kidney transplantation has a negative long-term impact on graft and patient outcomes

A systematic review and meta-analysis of factors contributing to post-kidney transplant anemia and the effect of erythropoietin-stimulating agents

BACKGROUND

The effects of various risk and associated factors on post-kidney transplant anemia (PTA) have not been fully compared and estimated. This meta-analysis aims to elucidate factors contributing to PTA and determine the influence of erythropoietin-stimulating agents (ESAs) on renal outcomes, thus offering potential pathways for enhanced management strategies post-transplant.

METHODS

A systematic review was conducted in electronical database. Studies reporting on risk factors (with cause-effect relationships) and associated factors (without definite cause-effect relationships) of PTA, and the effects of ESAs on post-kidney transplant outcomes, were included. Pooled odds ratios (ORs) and weighted mean differences (WMDs) were analyzed using random-effects models.

RESULTS

This systematic review encompassed 38,233 patients from 85 studies. Factors increased PTA risk included African American, older donor age, human antigen leukocyte mismatches, and low pre-transplant hemoglobin levels. Poor allograft function, high interleukine-6, Cytomegalovirus, delayed graft function, allograft rejections, immunosuppressive medications, and renin-angiotensin system blockades were associated with PTA. Native autosomal dominant polycystic kidney disease was a protective factor against PTA. Administration of ESAs with the aim of normalizing hemoglobin levels in patients with chronic allograft dysfunction slowed the decline in eGFR and reduce the risk of death, with a pooled OR of 0.36 (95% CI: 0.14 to 0.89; p = 0.040).

CONCLUSIONS

The risks and associated factors for PTA have been elucidated, underscoring the need for individualized treatment approaches. Late ESA therapy, aimed at hemoglobin normalization, suggests a renal-protective effect and reduced mortality, which should be considered in the management of PTA.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42024545330.

Risk factors and current state of therapy for anemia after kidney transplantation

Post-transplant anemia is one of the most common complications in kidney transplant recipients, severely affecting patient prognosis and quality of life, and is an independent predictor of graft kidney loss and patient mortality. However, our clinical understanding and the attention given to post-transplant anemia are currently insufficient. This paper reviews the current status, risk factors, and therapeutic progress in anemia after transplantation in kidney transplant recipients. We recommend that clinical staff pay attention to anemia and its complications in kidney transplant recipients and intervene early for anemia.

Treatment Options for Anemia in Kidney Transplant Patients: A Review

Anemia is common after kidney transplantation. The etiology may be multifactorial, such as causes of anemia in the general population and causes that are unique to the kidney transplant setting. Posttransplant anemia, particularly when severe, may be associated with adverse effects such as graft failure, mortality, and a decline in kidney function. After careful investigation, that is, having excluded or treated reversible causes of anemia, treatment of anemia in patients with a kidney transplant is based on iron supplementation or erythropoiesis-stimulating agents (ESA), although there are no specific guidelines on anemia management in this patient population. Iron therapy is often needed, but optimal and safe iron-deficiency management strategies remain to be defined. Evidence suggests that ESAs are safe and potentially associated with favorable outcomes. Better graft function has been reported with ESA use targeting hemoglobin levels higher than those recommended in the general population with chronic kidney disease and with no apparent increased risk of cardiovascular events. These results require further investigation. Data on the use of hypoxia-inducible factor inhibitors are limited. Prevention and treatment of anemia in kidney transplantation can improve patients' quality of life, life expectancy, allograft function, and survival.

Anemia and Erythrocytes: Behavior and Prevalence 1 Year After Kidney Transplant

INTRODUCTION

Renal transplantation presents multiple complications after its completion, some of them related to the behavior of hemoglobin levels. The objective of this study is to determine the behavior and prevalence of anemia and erythrocytosis in the first year after renal transplantation.

MATERIAL AND METHODS

A retrospective, observational study was conducted of a cohort of patients of the 21st Century National Medical Center in Mexico of transplants performed from January 1, 2013 to December 31, 2017. A total of 649 met the inclusion criteria. Pre-transplant hemoglobin (Hb) levels were determined, as well as levels 1 month, 3, 6, 9, and 12 months after transplantation, and the prevalence of anemia and erythrocytosis was determined in each month. Descriptive analysis was performed with measures of central tendency and measures of dispersion. The statistical program SPSS version 25 was used.

RESULTS

The mean pre-transplant Hb was 10.69 g/dL (standard deviation [SD] 2.04). One year after the renal transplant, Hb averaged 14.45 g/dL (SD 2.30), which meant an increase over the first year after renal transplantation of 3.76 g/dL. Pre-transplant anemia occurred in 73.1% of patients, and erythrocytosis in 0.1%; 12.9% of patients and 5.9% in erythrocytosis continued with anemia for a year.

CONCLUSIONS

Renal transplantation allows Hb levels to recover in a multifactorial way; however, the persistence of anemia and erythrocytes creates a study challenge in any transplant unit, due to their prevalence of 12.9 and 5.9% respectively.

Pre-Transplant Erythropoiesis-Stimulating Agent Hypo-Responsiveness and Post-Transplant Anemia

BACKGROUND

At the time of kidney transplantation (KT), almost all patients have anemia caused by low levels of endogenous erythropoietin (EPO), along with several other factors. After KT, anemia improves because of secretion of EPO from the allograft. But some recipients have persistent anemia. Whether or not erythropoiesis-stimulating agent (ESA) hypo-responsiveness before KT affects post-transplant anemia (PTA) remains unknown.

METHODS

Sixty-eight patients received KT between January 2007 and July 2012 through the Department of Urology at Kobe University Hospital, and 35 of these patients were enrolled. Exclusion criteria included age <18 years, unknown ESA dosage at transplantation, ESA start within 1 year after transplantation, and other criteria. We evaluated post-transplant hemoglobin (Hb) levels from the pre-transplant ESA responsive index (ERI): pre-transplant ESA dosage/Hb × body weight at 1 year after transplantation.

RESULTS

The mean (± SD) Hb of all patients rose from 11.3 ± 1.0 mg/dL to 12.7 ± 1.4 mg/dL at 1 year after transplantation (P < .01). The pre-transplant low ERI group (<10) showed significantly higher hemoglobin levels compared with the pre-transplant high ERI group (≥ 10; 12.9 ± 1.14 mg/dL versus 11.8 ± 1.76 mg/dL, respectively; P = .03).

CONCLUSIONS

ESA hypo-responsiveness before KT carried over after KT. Low pre-transplant ERI might be a sentinel marker for PTA.

Post-transplantation Anemia Predicts Cardiovascular Morbidity and Poor Graft Function in Kidney Transplant Recipients

OBJECTIVE

We aimed to investigate whether low post-transplantation-period hemoglobin levels are predictive of cardiovascular morbidity in terms of left ventricular (LV) hypertrophy and vascular stiffness and to determine the contributing factors of post-transplantation anemia in kidney transplant (KT) recipients.

METHODS

One hundred fifty (mean age, 38.9 ± 10.8 y; 113 male) KT recipients with functioning grafts were enrolled in the study. All subjects underwent clinical and laboratory evaluations (24-hour urinary protein loss, complete blood count) and transthoracic echocardiography to assess LV systolic function. Arterial stiffness was measured by means of carotid-femoral pulse-wave velocity (PWV). Mean hemoglobin levels were analyzed at the 1st, 6th, 12th, and 24th months after transplantation. Patients were divided into 2 groups according to presence of anemia: patients with anemia (group 1; n = 120) and normal (group 2; n = 30).

RESULTS

PWV values (6.8 ± 1.9 m/s vs 6.4 ± 1.1 m/s in groups 1 and 2, respectively; P = .002) and LV mass index (LVMI; 252.1 ± 93.7 g/m(2) vs 161.2 ± 38.5 g/m(2) groups 1 and 2, respectively; P = .001) were significantly higher in group 1. Estimated glomerular filtration rate and (64 ± 28.5 m/min vs 77.8 ± 30 m/min in groups 1 and 2, respectively; P = .001) LV systolic function (57.2 ± 5.8% vs 77.8 ± 30% in groups 1 and 2, respectively; P < .005) were significantly lower in group 1. In regression analysis, LV systolic function and LVMI were predictors of post-transplantation hemoglobin levels.

CONCLUSIONS

Post-transplantation anemia contributes to cardiovascular morbidity by deteriorating LV function and increasing PWV and is therefore associated with poor prognosis for graft survival. Early correction of post-transplantation anemia, especially with the use of erythropoietin, may be beneficial for both graft and recipient survivals.