Spectrum of anemia after kidney transplantation: pathophysiology and therapeutic implications

The incidence and factors associated with anemia in elective surgical patients admitted to a surgical intensive care unit: a retrospective cohort study

BACKGROUND

Anemia is a frequently reported and commonly documented issue in intensive care units. In surgical intensive care units, more than 90% of patients are found to be anemic. It is a hematologic factor that contributes to extended mechanical ventilation, sepsis, organ failure, longer hospitalizations in critical care units, and higher mortality. Thus, this study aimed to determine the incidence and identify factors associated with anemia in elective surgical patients admitted to the surgical intensive care unit.

METHODS

A retrospective follow-up study involving 422 hospitalized patients was carried out between December 2019 and December 2022 in the surgical intensive care unit after elective surgery at Tikur-Anbessa Specialized Hospital, Addis Ababa, Ethiopia. Data were gathered from the patients' charts, and study participants were chosen using methods of systematic random sampling. SPSS 26 (the statistical software for social science, version 26) was used to analyze the data. Bivariable and multivariable binary logistic regression were used to examine associations between variables.

RESULTS

The incidence of anemia in elective surgical patients admitted to the intensive care unit was 69.9% (95% CI 65.4-74.5%). American Society of Anesthesiologists' class III (ASA III) [AOR: 8.53, 95% CI 1.92-13.8], renal failure [AOR:2.53, 95% CI (1.91-5.81)], malignancy [AOR: 2.59, 95% CI (1.31-5.09)], thoracic surgery [AOR: 4.07, 95% CI (2.11-7.87)], urologic surgery [AOR: 6.22, 95% CI (2.80-13.80)], and neurosurgery [AOR: 4.51, 95% CI (2.53-8.03)] were significantly associated with anemia in surgical patients admitted to the intensive care unit.

CONCLUSION

More than two-thirds of the intensive care unit-admitted surgical patients experienced anemia. An American Society of Anesthesiologists' (ASA III score), renal failure, malignancy, thoracic surgery, urologic surgery, and neurosurgery were significantly associated with this condition. Early identification helps to institute preventive and therapeutic measures.

Anemia in Patients After Stem Cell Transplantation and in Kidney Transplant Recipients

Hematopoietic stem cell transplant (HSCT) is the treatment of choice in various hematologic diseases, and kidney transplantation (KTx) is the best therapy for end-stage kidney disease. Chronic kidney disease (CKD) occurs relatively often after both types of transplantations. Anemia after both HSCT and KTx may be due to CKD and other reasons. This study aimed to assess the prevalence of anemia to CKD in 156 prevalent patients after HSCT and 80 after KTx. According to the World Health Organization's definition (hemoglobin <13 g/dL for men and <12 g/dL for women), the prevalence of anemia in the studied cohort after HSCT was 13% in women and 35% in men and for those after KTx, it was29% in men and 11%. Anemia in KTx was found in 46% of patients, whereas CKD was present in 53%. After HSCT, anemia was associated with CKD in 56% of women and 17% of men. In KTx, anemia and CKD was diagnosed in 21% of patients. Patients with anemia after KTx had significantly lower glomerular filtration rate (GFR), hemoglobin, and significantly higher creatinine levels. Age was related to the estimated GFR (eGFR; r = -0.39, P < .001) in patients who underwent HSCT and had anemia. In patients without anemia, age was negatively related to eGFR (r = -0.56, P < .001) and the hemoglobin-to-platelet count (r = 0.62, P < .001). In KTx, hemoglobin was related to eGFR (r = 0.35, P < .001), and age was related to eGFR (r = -0.20, P < .05). The type of induction therapy immunosuppressive regimen (anti-thymocyte globulin vs basiliximab vs no induction) did not affect the prevalence of anemia in the KTx population studied. Anemia is relatively common in CKD after HSCT. In both CKD and coexistent anemia, nephrology referral is to be considered to optimize therapy, including nephroprotection.

Relationship of hemoglobin levels with outcomes in deceased donor kidney transplant: a retrospective cohort study

INTRODUCTION

Anemia is frequent in patients undergoing replacement therapy for kidney failure. Anemia in the pre- and post-transplantation period might be related to kidney transplant outcomes. The current study therefore sought to assess the relationship between anemia, delayed allograft function (DGF), chronic kidney allograft dysfunction (CAD), and death from any cause following kidney transplantation from a deceased donor.

METHODS

This was a retrospective study with 206 kidney transplant patients of deceased donors. We analyzed deceased donors' and kidney transplant patients' demographic data. Moreover, we compared biochemical parameters, anemia status, and medicines between DGF and non-DGF groups. Afterward, we performed a multivariate analysis. We also evaluated outcomes, such as CAD within one year and death in ten years.

RESULTS

We observed a lower frequency of pre-transplant hemoglobin concentration (Hb) but higher frequency of donor-serum creatinine and red blood transfusion within one week after transplantation in the group with DGF. In addition, there was an independent association between Hb concentration before transplantation and DGF [OR 0.252, 95%CI: 0.159-0.401; p < 0.001]. There was also an association between Hb concentration after six months of kidney transplantation and both CAD [OR 0.798, 95% CI: 0.687-0.926; p = 0.003] and death from any cause.

CONCLUSION

An association was found between pre-transplantation anemia and DGF and between anemia six months after transplantation and both CAD and death by any cause. Thus, anemia before or after transplantation affects the outcomes for patients who have undergone kidney transplantation from a deceased donor.

Association between blood transfusion after kidney transplantation and risk for the development of de novo HLA donor-specific antibodies and poor clinical outcomes: A single-center retrospective study

BACKGROUND

Blood transfusion after kidney transplantation may increase the risk of sensitization and development of de novo human leukocyte antigen (HLA) donor-specific antibodies (DSAs). This study aimed to evaluate whether blood transfusion during the first year after kidney transplantation influences the development of de novo DSAs and clinical outcomes of kidney transplantation recipients.

METHODS

This retrospective cohort study included nonsensitized first-time kidney transplantation recipients at Tianjin First Central Hospital from 2010 to 2022. The incidence of de novo DSA development and clinical outcomes between the groups were compared. Luminex single antigen beads were used to monitor DSAs.

RESULTS

Of the 538 non-HLA-sensitized kidney transplantation recipients included in the study, 164 patients who received at least one unit of leukoreduced red blood cell transfusion within the first year (the transfused group), whereas the remaining 374 patients received no blood transfusion (the non-transfused group). Our analysis showed that there was a significant difference in the development of de novo DSAs and de novo anti-class I HLA-Ab between the two groups. Indeed, the transfused recipients had a higher serum creatinine and lower estimated glomerular filtration rate (eGFR) at 1-, 6-, and 12-month (all p > 0.05) after transplantation. Futhermore, a higher incidence of CMV infection, antibody-mediated rejection (AMR), hyper acute rejection (HAR), and delayed graft function (DGF) was identified in the transfused group (all p < 0.05). The graft survival was lower in the transfused group compared with patients in the non-transfused group (P = 0.002). Blood transfusion post-transplantation was a risk factor for de novo DSAs development but not an independent predictive factor for AMR and graft loss (odds ratio = 2.064 [1.243-3.429], p = 0.005).

CONCLUSIONS

Our study showed that blood transfusion after transplantation is associated with the occurrence of de novo DSAs increasing an immunological risk for poor clinical outcomes for kidney transplantation recipients.

Impact of iron status on kidney outcomes in kidney transplant recipients

Iron plays an important role in hemodynamics and the immunity, independent of anemia. Since dynamic changes occur in iron storage after kidney transplantation (KT), we investigated the association between iron status and kidney outcomes in KT patients. We analyzed data from the KoreaN cohort study for Outcome in patients With KT (KNOW-KT). The iron status was classified into three groups based on ferritin or transferrin saturation (TSAT) levels one year after KT, with reference ranges of 20‒35% and 100‒300 ng/mL for TSAT and ferritin, respectively. The primary outcome was the composite outcome, which consisted of death, graft failure, and an estimated glomerular filtration rate decline ≥ 50%. In total, 895 patients were included in the final analysis. During a median follow-up of 5.8 years, the primary outcome occurred in 94 patients (19.8/1000 person-years). TSAT levels decreased one year after KT and thereafter gradually increased, whereas ferritin levels were maintained at decreased levels. The adjusted hazard ratios (95% confidence intervals) for the composite outcome were 1.67 (1.00-2.77) and 1.20 (0.60-2.40) in the TSAT > 35% and ferritin > 300 ng/mL groups, respectively. High iron status with high TSAT levels increases the risk of graft failure or kidney functional deterioration after KT.

Anemia in Pediatric Kidney Transplant Recipients-Etiologies and Management

Posttransplant anemia (PTA) is a common complication of pediatric kidney transplantation, with a prevalence ranging from 22 to 85%. PTA is categorized as early (within 6 months posttransplant) and late (>6 months posttransplant). Early PTA is typically associated with surgical blood losses and iron deficiency. Late PTA primarily results from graft dysfunction; however, iron deficiency, drug toxicity, and posttransplant inflammation also play a role. PTA is more severe compared with the anemia in glomerular-filtration-rate matched patients with native chronic kidney disease. Treatment of PTA is directed toward the underlying cause. Erythropoiesis stimulating agents (ESA) are effective; however, their use is limited in the transplant setting. Timely diagnosis and treatment of PTA are vital to prevent long-term adverse outcomes in pediatric transplant recipients.

An evaluation of PJP prophylaxis and anemia among renal transplant recipients

BACKGROUND

Dapone and atovaquone are therapeutic options for PJP prophylaxis in renal transplant recipients. The objective of this study was to evaluate the incidence of anemia in renal transplant recipients receiving these agents.

METHODS

This is an IRB-approved, retrospective analysis of adult renal transplant recipients who received either dapsone or atovaquone. The primary endpoint was the change in hemoglobin within 90 days of drug initiation. Other endpoints of interest included incidence and management of anemia at multiple time points post-transplant. Categorical variables were compared with Pearson's chi-squared or Fischer's exact test and continuous data were compared utilizing Wilcoxon rank-sum test. Statistical analyses were performed using Stata 14.2.

RESULTS

A total of 478 patients were screened for inclusion; 50 patients were evaluated in both the dapsone and atovaquone groups. In the dapsone and atovaquone groups, the median age was 52 and 50.5 years, 44% and 42% were Caucasian, and median time to treatment initiation was 27 and 39 days post-transplant, respectively. All patients receiving dapsone had normal G6PD function. There was no difference in baseline hemoglobin between groups (9.7 g/dL vs 9.8 g/dL, P = .83). The median nadir hemoglobin values were 8.6 g/dL and 9.6 g/dL in the dapsone and atovaquone groups, respectively (P = .047). The median decrease in hemoglobin from baseline to nadir was 1.3 g/dL in dapsone patients and 0.2 g/dL in atovaquone patients (P = .001). Dapsone was discontinued in 46% of patients, whereas atovaquone was discontinued in 18% (P = .001).

CONCLUSION

Among renal transplant recipients with normal G6PD activity, dapsone is associated with greater hemoglobin reductions and rates of drug discontinuation as compared to atovaquone.

Haematological disorders following kidney transplantation

Transplantation offers cure for some haematological cancers, end-stage organ failure, but at the cost of long-term complications. Renal transplantation is the best-known kidney replacement therapy and it can prolong end-stage renal disease patient lives for decades. However, patients after renal transplantation are at a higher risk of developing different complications connected not only with surgical procedure but also with immunosuppressive treatment, chronic kidney disease progression and rejection processes. Various blood disorders can develop in post-transplant patients ranging from relatively benign anaemia through cytopenias to therapy-related myelodysplasia and acute myeloid leukaemia (AML) and post-transplant lymphoproliferative disorders followed by a rare and fatal condition of thrombotic microangiopathy and haemophagocytic syndrome. So far literature mainly focused on the post-transplant lymphoproliferative disease. In this review, a variety of haematological problems after transplantation ranging from rare disorders such as myelodysplasia and AML to relatively common conditions such as anaemia and iron deficiency are presented with up-to-date diagnosis and management.

Impact of immediate post-transplant parenteral iron therapy on the prevalence of anemia and short-term allograft function in a cohort of pediatric and adolescent renal transplant recipients

Anemia is common but under-diagnosed and often inadequately treated in KTX recipients. ID is the major cause of early-onset anemia. We introduced routine use of parenteral (IV) iron in patients (2-18 years) who had KTX between January 2011 and December 2015. We explored the clinical benefits of this practice by comparing the iron-treated subjects [TX] with historical controls who had KTX between 2005 and 2010. The prevalence of anemia at 6 months (early-onset) for the cohort (both the study group and controls) was 55% and for anemia at 12 months (late-onset) was 60%. Although cause-effect relationship may not be proven in a retrospective study design, there was a significant greater frequency of ID and anemia at 3 (P < .02) and 6 months (P < .04), and a reduced allograft function (eGFR < 60 mL/min/1.73 m² ) at 12 (P = .03) and 24 months (P = .04) of KTX in the control arm. Furthermore, a greater proportion of the control arm required either ESA (P = .03) or blood transfusion (P = .04) as a rescue treatment for moderate-to-severe anemia. In conclusion, routine parenteral iron treatment was associated with a lower prevalence of early- and late-onset anemia, and a lower requirement for either ESA rescue or blood transfusion.

Characteristics of Anemia and Iron Deficiency After Kidney Transplant

BACKGROUND

Numerous studies have shown that iron deficiency is common in patients with end-stage renal disease. However, change of iron deficiency after kidney transplant (KT) is not fully understood. This study was undertaken to examine sequential changes of iron level after KT.

METHODS

A total of 1080 KT recipients enrolled in a multicenter observational cohort study between July 2012 and August 2018. A total of 786 patients with transferrin saturation and ferritin level at pretransplant and 1 year after KT were reviewed. Iron deficiency was defined as ferritin <200 ng/mL and total saturation of transferrin (TSAT) < 20%. Anemia was defined as hemoglobin (Hb) < 13 g/dL (male) or <12 g/dL (female).

RESULTS

Hemoglobin at 1 year after KT was higher than Hb at KT (13.64 [SD, 1.87] g/dL vs 10.53 [SD, 1.63] g/dL; P < .001). The TSAT decreased from baseline at 1 year after KT (33.89% [SD, 18.73%] vs 29.09% [SD, 14.54%]; P < .001), and ferritin level decreased from baseline at 1 year (190.63 [SD, 217.43] ng/mL vs 141.39 [194.25] ng/mL; P < .001). In patients with anemia at pretransplant, the group with anemia at 1 year after KT (persistent group) and the group without anemia at 1 year after KT (improved group) were compared. The persistent group showed higher pretransplant TSAT, lower 1-year TSAT, and lower estimated glomerular filtration rate at 1 year after KT than the improved group. In multivariate analysis, low ferritin at KT, low TSAT at 1 year, and high ferritin at 1 year were the risk factors for low Hb level at 1 year after adjusting multiple variables.

CONCLUSION

Anemia improved within 1 year after KT, although patients with iron deficiency increased. While ferritin reflected the inflammatory status, low TSAT at 1 year after KT was a risk factor for anemia at 1 year after KT.

Development and future deployment of a 5 years allograft survival model for kidney transplantation

AIM

Identifying kidney transplant patients at highest risk for graft loss prior to loss may allow for effective interventions to improve 5 years survival.

METHODS

We performed a 10 years retrospective cohort study of adult kidney transplant recipients (n = 1747). We acquired data from electronic health records, United Network of Organ Sharing, social determinants of health, natural language processing data extraction, and real-time capture of dynamically evolving clinical data obtained within 1 year of transplant; from which we developed a 5 years graft survival model.

RESULTS

Total of 1439 met eligibility; 265 (18.4%) of them experienced graft loss by 5 years. Graft loss patients were characterized by: older age, being African-American, diabetic, unemployed, smokers, having marginal donor kidneys and cardiovascular comorbidities. Predictive dynamic variables included: low mean blood pressure, higher pulse pressures, higher heart rate, anaemia, lower estimated glomerular filtration rate peak, increased tacrolimus variability, rejection and readmissions. This Big Data analysis generated a 5 years graft loss model with an 82% predictive capacity, versus 66% using baseline United Network of Organ Sharing data alone.

CONCLUSION

Our analysis yielded a 5 years graft loss model demonstrating superior predictive capacity compared with United Network of Organ Sharing data alone, allowing post-transplant individualized risk-assessed care prior to transitioning back to community care.

Anemia in chronic kidney disease

Anemia is common and associated with adverse outcomes in children with chronic kidney disease (CKD). Many factors contribute to declining hemoglobin as CKD progresses, but impaired production of erythropoietin by failing kidneys is a central cause. Hepcidin-mediated iron restriction also contributes to anemia by downregulating both intestinal iron absorption and release of stored iron for erythropoiesis. The core components of anemia management remain erythropoiesis-stimulating agents (ESA) and iron supplementation, but despite these therapies, a substantial number of children remain anemic. Although escalating ESA dose to target higher hemoglobin has been associated with adverse outcomes in adults, no trials have investigated this association in children, and maintaining hemoglobin levels in a narrow range with conservative ESA dosing is challenging. Judicious use of iron supplementation can enhance the response to ESAs, but the iron storage markers most commonly used in clinical practice have limitations in distinguishing which patients will benefit most from additional iron. Several novel anemia therapies, including hypoxia-inducible factor stabilizers, prolyl hydroxylase inhibitors, and dialysate-delivered iron supplements, have been developed and may offer options for alternative anemia management. However, the safety and efficacy of these agents in children with CKD has yet to be assessed.