Posttransplant Diabetes Mellitus and Immunosuppression Selection in Older and Obese Kidney Recipients

Association of COVID-19 With Risk of Posttransplant Diabetes Mellitus

BACKGROUND

Posttransplant diabetes mellitus (PTDM) is an important complication for solid organ transplant recipients (SOTRs). COVID-19 has been associated with an increased risk of incident diabetes in the general population. However, the association between COVID-19 and new-onset PTDM has not been explored.

METHODS

Using the National COVID Cohort Collaborative Enclave, we conducted a cohort study of adults without diabetes receiving a solid organ transplant (heart, lung, kidney, or liver) in the United States between April 1, 2020, and March 31, 2023, with and without a first diagnosis of COVID-19 (COVID+ versus COVID-) within 180 d of SOT. We propensity score matched a single COVID+ SOTR with a COVID- SOTR who was diabetes free at the same point posttransplant. Within this matched cohort, we used multivariable Cox proportional hazards models to examine the adjusted risk of PTDM associated with COVID+.

RESULTS

Among 1342 COVID+ SOTRs matched to 1342 COVID- SOTRs, the crude rate of newly diagnosed PTDM in the 2 y post-COVID was 17% in those with versus 13% in those without COVID-19 (P = 0.007). COVID-19 was significantly associated with new PTDM (adjusted hazard ratio, 1.37; 95% confidence interval, 1.12-1.68 at 2 y).

CONCLUSIONS

Similar to other viral infections, COVID-19 is associated with an increased risk of PTDM in SOTRs.

The incidence and risk factors of post-transplant diabetes mellitus in living donor kidney transplantation patients: a retrospective study

BACKGROUND

Post-transplant diabetes mellitus (PTDM) is a well-known complication of kidney transplantation that significantly impacts recipient morbidity and mortality. Over the recent years, the incidence of PTDM has increased considerably worldwide. Therefore, the primary purpose of this study was to evaluate the incidence and risk factors for PTDM in living donor kidney transplantation patients in Riyadh, Saudi Arabia.

METHODS

A retrospective cohort study was conducted at a tertiary transplant center in Riyadh, Saudi Arabia, and data were extracted between February 2016 and March 2022. Patients aged ≥ 18 years who underwent renal transplant with at least one year of post-transplant follow-up were included in the analysis, and their medical records were comprehensively reviewed. Patients < 18 years of age, history of diabetes mellitus, other organ transplants, or those who underwent transplantation outside the Kingdom of Saudi Arabia were excluded from the study.

RESULTS

The study included 247 living donor kidney transplant patients, with a mean age of 39.5 ± 14.6 years. 17.0% of the patients were diagnosed with PTDM. Patient age and fasting glucose levels at 6-months and 12-months after transplantation were found to be significant risk factors for the development of PTDM.

CONCLUSION

An increased occurrence of PTDM emphasizes the importance of identifying high-risk patients prior to transplantation and implementing early interventions to prevent potential complications that could affect graft and patient survival.

Association of early steroid withdrawal with kidney transplant outcomes in first-transplant and retransplant recipients

BACKGROUND AND HYPOTHESIS

Early steroid withdrawal (ESW) is often preferred over conventional steroid maintenance (CSM) therapy for kidney transplant recipients with low immunological risks because it may minimize immunosuppression-related adverse events while achieving similar transplant outcomes. However, the risk-benefit balance of ESW could be less favorable in retransplant recipients given their unique immunological risk profile. We hypothesized that the association of ESW with transplant outcomes would differ between first-transplant and retransplant recipients.

METHODS

To assess whether the impact of ESW differs between first and retransplant recipients, we studied 210 086 adult deceased-donor kidney transplant recipients using the Scientific Registry of Transplant Recipients. Recipients who discontinued maintenance steroids before discharge from transplant admission were classified with ESW; all others were classified with CSM. We quantified the association of ESW (vs. CSM) with acute rejection, death-censored graft failure, and death, addressing retransplant as an effect modifier, using logistic/Cox regression with inverse probability weights to control for confounders.

RESULTS

In our cohort, 26 248 (12%) were retransplant recipients. ESW was used in 30% of first-transplant and 20% of retransplant recipients. Among first-transplant recipients, ESW was associated with no significant difference in acute rejection (aOR = 1.04 [95% CI = 1.00-1.09]), slightly higher hazard of graft failure (HR = 1.09 [95% CI = 1.05-1.12]), and slightly lower mortality (HR = 0.93 [95% CI = 0.91-0.95]) compared to CSM. Nonetheless, among retransplant recipients, ESW was associated with notably higher risk of acute rejection (OR = 1.42 [95% CI = 1.29-1.57]; interaction p < 0.001) and graft failure (HR = 1.24 [95% CI = 1.14-1.34]; interaction p = 0.003), and similar mortality (HR = 1.01 [95% CI = 0.94-1.08]; interaction p = 0.04).

CONCLUSIONS

In retransplant recipients, the negative impacts of ESW on transplant outcomes appear to be non-negligible. A more conservatively tailored approach to ESW might be necessary for retransplant recipients.

Application of HLA molecular level mismatching in ethnically diverse kidney transplant recipients receiving a steroid-sparing immunosuppression protocol

Defining HLA mismatch at the molecular compared with the antigen level has been shown to be superior in predicting alloimmune responses, although data from across different patient populations are lacking. Using HLA-Matchmaker, HLA-EMMA and PIRCHE-II, this study reports on the association between molecular mismatch (MolMM) and de novo donor-specific antibody (dnDSA) in an ethnically diverse kidney transplant population receiving a steroid-sparing immunosuppression protocol. Of the 419 patients, 51 (12.2%) patients had dnDSA. De novo DSA were seen more frequently with males, primary transplants, patients receiving tacrolimus monotherapy, and unfavorably HLA-matched transplants. There was a strong correlation between MolMM load and antigen mismatch, although significant variation of MolMM load existed at each antigen mismatch. MolMM loads differed significantly by recipient ethnicity, although ethnicity alone was not associated with dnDSA. On multivariate analysis, increasing MolMM loads associated with dnDSA, whereas antigen mismatch did not. De novo DSA against 8 specific epitopes occurred at high frequency; of the 51 patients, 47 (92.1%) patients with dnDSA underwent a pretreatment biopsy, with 21 (44.7%) having evidence of alloimmune injury. MolMM has higher specificity than antigen mismatching at identifying recipients who are at low risk of dnDSA while receiving minimalist immunosuppression. Immunogenicity consideration is important, with more work needed on identification, especially across different ethnic groups.

The use of lymphocyte-depleting antibodies in specific populations of kidney transplant recipients: A systematic review and meta-analysis

BACKGROUND

Recommendations of the use of antibody induction treatments in kidney transplant recipients (KTR) are based on moderate quality and historical studies. This systematic review aims to reevaluate, based on actual studies, the effects of different antibody preparations when used in specific KTR subgroups.

METHODS

We searched MEDLINE and CENTRAL and selected randomized controlled trials (RCT) and observational studies looking at different antibody preparations used as induction in KTR. Comparisons were categorized into different KTR subgroups: standard, high risk of rejection, high risk of delayed graft function (DGF), living donor, and elderly KTR. Two authors independently assessed the risk of bias.

RESULTS

Thirty-seven RCT and 99 observational studies were finally included. Compared to anti-interleukin-2-receptor antibodies (IL2RA), anti-thymocyte globulin (ATG) reduced the risk of acute rejection at two years in standard KTR (RR 0.74, 95%CI 0.61-0.89) and high risk of rejection KTR (RR 0.55, 95%CI 0.43-0.72), but without decreasing the risk of graft loss. We did not find significant differences comparing ATG vs. alemtuzumab or different ATG dosages in any KTR group.

CONCLUSIONS

Despite many studies carried out on induction treatment in KTR, their heterogeneity and short follow-up preclude definitive conclusions to determine the optimal induction therapy. Compared with IL2RA, ATG reduced rejection in standard-risk, highly sensitized, and living donor graft recipients, but not in high DGF risk or elderly recipients. More studies are needed to demonstrate beneficial effects in other KTR subgroups and overall patient and graft survival.

Obesity and kidney transplantation

PURPOSE OF REVIEW

Obesity has reached epidemic proportions in the United States. It is a risk factor for developing, among others, heart disease, stroke, type 2 diabetes, and chronic kidney disease (CKD), and thus a major public health concern and driver of healthcare costs. Although the prevalence of obesity in the CKD/end-stage kidney disease population is increasing, many obese patients are excluded from the benefit of kidney transplant based on their BMI alone. For this reason, we sought to review the experience thus far with kidney transplantation in obese patients and associated outcomes.

RECENT FINDINGS

Obesity is associated with a lower rate of referral and waitlisting, and lower likelihood of kidney transplantation. Despite increased risk for early surgical complications and delayed graft function, experience from multiple centers demonstrate a clear survival benefit of transplantation over dialysis in most obese patients, and comparable graft and patient survival rates to nonobese recipients.

SUMMARY

Data suggest that long-term transplant outcomes among obese recipients are similar to those among nonobese. Strategies to achieve pretransplant weight reduction and minimally invasive surgical techniques may further improve results of kidney transplantation in obese recipients.

Maximizing opportunities for kidney transplantation in older adults

PURPOSE OF REVIEW

To summarize the current state of evidence related to the outcomes of older adults who need and receive kidney transplants, and strategies to facilitate appropriate transplant access in this at-risk group.

RECENT FINDINGS

Older adults are a rapidly growing subgroup of the kidney transplant waitlist. Compared to younger adults, older kidney transplant recipients have increased mortality after kidney transplant and lower death-censored graft survival. In determining suitability for transplantation in older patients, clinicians must balance procedural and immunosuppression-related risk with incremental survival when compared with dialysis. To appropriately increase access to transplantation in this population, clinicians and policy makers consider candidates' chronological age and frailty, as well as the quality of and waiting time for a donated allograft. Given risk of deterioration prior to transplant, candidates should be rapidly evaluated, listed, and transplanted using living donor and or less than ideal deceased donor organs when available.

SUMMARY

Access to transplantation for older adults can be increased through targeted interventions to address frailty and reduce waiting times through optimized organ use. Focused study and educational interventions for patients and providers are needed to improve the outcomes of this vulnerable group.

Distinct phenotypes of kidney transplant recipients aged 80 years or older in the USA by machine learning consensus clustering

Objectives

This study aimed to identify distinct clusters of very elderly kidney transplant recipients aged ≥80 and assess clinical outcomes among these unique clusters.

Design

Cohort study with machine learning (ML) consensus clustering approach.

Setting and participants

All very elderly (age ≥80 at time of transplant) kidney transplant recipients in the Organ Procurement and Transplantation Network/United Network for Organ Sharing database database from 2010 to 2019.

Main outcome measures

Distinct clusters of very elderly kidney transplant recipients and their post-transplant outcomes including death-censored graft failure, overall mortality and acute allograft rejection among the assigned clusters.

Results

Consensus cluster analysis was performed in 419 very elderly kidney transplant and identified three distinct clusters that best represented the clinical characteristics of very elderly kidney transplant recipients. Recipients in cluster 1 received standard Kidney Donor Profile Index (KDPI) non-extended criteria donor (ECD) kidneys from deceased donors. Recipients in cluster 2 received kidneys from older, hypertensive ECD deceased donors with a KDPI score ≥85%. Kidneys for cluster 2 patients had longer cold ischaemia time and the highest use of machine perfusion. Recipients in clusters 1 and 2 were more likely to be on dialysis at the time of transplant (88.3%, 89.4%). Recipients in cluster 3 were more likely to be preemptive (39%) or had a dialysis duration less than 1 year (24%). These recipients received living donor kidney transplants. Cluster 3 had the most favourable post-transplant outcomes. Compared with cluster 3, cluster 1 had comparable survival but higher death-censored graft failure, while cluster 2 had lower patient survival, higher death-censored graft failure and more acute rejection.

Conclusions

Our study used an unsupervised ML approach to cluster very elderly kidney transplant recipients into three clinically unique clusters with distinct post-transplant outcomes. These findings from an ML clustering approach provide additional understanding towards individualised medicine and opportunities to improve care for very elderly kidney transplant recipients.

New-Onset Diabetes Mellitus in Post-renal Transplant Patients on Tacrolimus and Mycophenolate: A Systematic Review

A frequent complication in kidney transplantation is post-transplant diabetes mellitus (PTDM). The primary goal of this study is to review the risk factors and preventive methods and compare the different available anti-diabetic medications for the management of PTDM. We searched databases like Pubmed and Google Scholar for related articles using specific terms and phrases. Following a thorough investigation, we applied the inclusion and exclusion criteria and completed a quality assessment. Modifiable risk factors have a significant role in the development of PTDM. The combinations of immunosuppressive treatment tacrolimus (TAC), cyclosporine A (CYC), and everolimus (EVL), steroids increase the incidence of PTDM significantly. Insulin is the most effective treatment for PTDM in the early transplant period; however, oral anti-diabetic medications look promising. Further clinical trials are required to determine the optimum treatment method for reducing the occurrence of PTDM and treating the existing condition with novel anti-hyperglycemic medications.

The Association of Pre-Transplant C-Peptide Level with the Development of Post-Transplant Diabetes: A Cohort Study

Background

Post-transplant diabetes mellitus (PTDM) is an important complication after kidney transplantation that results in reduced patient and allograft survival. Although there are established risk factors for PTDM, whether pretransplant C-peptide levels associate with PTDM is unknown. Therefore, in this study, we aimed to examine the association of pretransplant C-peptide levels with PTDM.

Methods

This was a cohort study of nondiabetic adult patients who underwent kidney transplant in Nova Scotia, Canada, between January 1, 2016, and March 31, 2021, with fasting C-peptide levels measured before transplant. Multivariable logistic regression was used to determine the association of pretransplant C-peptide (dichotomized around the median) with PTDM at 1 year post transplant. Given the known association between pretransplant obesity and PTDM, we repeated our primary analysis in a cohort restricted to a BMI of 20-35 kg/m².

Results

The median C-peptide value was 3251 (Q1 2480, Q3 4724); pretransplant C-peptide level was dichotomized at 3000 pmol/L. PTDM occurred in 25 (19%) individuals. Thirty percent of patients in the high and only 2% of patients in the low C-peptide groups developed PTDM (P<0.001). A C-peptide level ≥3000 pmol/L was strongly associated with PTDM in multivariable analysis (OR=18.9, 95% CI, 2.06 to 174.2). In a restricted cohort with a BMI of 20-35 kg/m², an elevated pretransplant C-peptide remained independently associated with the risk of PTDM (OR=15.7, 95% CI, 1.64 to 150.3). C-peptide was the only factor independently associated with PTDM in this restricted BMI cohort.

Conclusions

A pretransplant C-peptide level ≥3000 pmol/L was associated with a nearly 20-fold increased odds of PTDM at 1 year post kidney transplantation. Identifying patients with high pretransplant C-peptide levels may therefore help identify those at risk for PTDM who may benefit from focused preventative and therapeutic interventions and support.

Kidney Transplantation, Immunosuppression and the Risk of Fracture: Clinical and Economic Implications

Rationale & Objective

Disorders of bone and mineral metabolism frequently develop with advanced kidney disease, may be exacerbated by immunosuppression after kidney transplantation, and increase the risk of fractures.

Study Design

Retrospective database study.

Setting & Participants

Kidney-only transplant recipients aged ≥18 years from 2005 to 2016 in the United States captured in US Renal Data System records, which integrate Organ Procurement and Transplantation Network/United Network for Organ Sharing records with Medicare billing claims.

Exposures

Various immunosuppression regimens in the first 3 months after kidney transplantation.

Outcomes

The development of fractures, as ascertained using diagnostic codes on Medicare billing claims.

Analytical Approach

We used multivariable Cox regression with inverse propensity weighting to compare the incidence of fractures >3 months-to-3 years after kidney transplantation associated with various immunosuppression regimens compared to a reference regimen of antithymocyte globulin (TMG) or alemtuzumab (ALEM) with tacrolimus + mycophenolic acid + prednisone using inverse probability treatment weighting.

Results

Overall, fractures were identified in 7.5% of kidney transplant recipients (women, 8.8%; men, 6.7%; age < 55 years, 5.9%; age ≥ 55 years, 9.3%). In time-varying regression, experiencing a fracture was associated with a substantially increased risk of subsequent death within 3 months (adjusted hazard ratio [aHR], 3.06; 95% confidence interval [CI], 2.45-3.81). Fractures were also associated with increased Medicare spending (first year: $5,122; second year: $10,890; third year: $11,083; [P < 0.001]). Induction with TMG or ALEM and the avoidance or early withdrawal of steroids significantly reduced the risk of fractures in younger (aHR, 0.63; 95% CI, 0.54-0.73) and older (aHR, 0.83; 95% CI, 0.74-0.94) patients. The avoidance or early withdrawal of steroids with any induction was associated with a reduced risk of fractures in women.

Limitations

This was a retrospective study which lacked data on immunosuppression levels.

Conclusions

Fractures after kidney transplantation are associated with significantly increased mortality risk and costs. The early avoidance or early withdrawal of steroids after induction with TMG or ALEM reduces the risk of fractures after kidney transplantation and should be considered for patients at high-risk of this complication, including older adults and women.