Unrepresented human leucocyte antigen alleles in single-antigen bead assays: A single-centre cohort study.

Human leucocyte antigen (HLA) alleles may generate antibodies that are undetectable by routine single-antigen beads (SABs) assays if their unique epitopes are unrepresented. We aimed to describe the prevalence and explore the potential impact of unrepresented HLA alleles in standard SAB kits in our cohort. All individuals who had undergone two-field HLA typing (HLA-A/B/C/DRB1/DQA1/-DQB1/-DPA1/-DPB1) from February 2021 to July 2023 were included. Two-field HLA-DRB3/4/5 typing was imputed. Each unrepresented allele was compared with the most similar represented allele in the standard LABScreen, LABScreen ExPlex (One Lambda) and the LIFECODES (Immucor) SAB kits. Differences in eplet expression (HLA Eplet Registry) were identified. Differences in three-dimensional molecular structures were visualized using generated models (SWISS-MODEL). Two-field HLA typing was performed for 116 individuals. Overall, 16.7% of all HLA alleles, found in 36.2% of individuals, were unrepresented by all SAB test kits. Four eplets, found in 12.9% of individuals, were unrepresented in at least 1 SAB kit. Non-Chinese individuals were more likely to have unrepresented HLA alleles and eplets than Chinese individuals. There were differences in HLA allele and eplet representation amongst the different SAB test kits. Use of supplementary SAB test kits may improve HLA allele and eplet representation. Although some HLA alleles were unrepresented, most epitopes were represented in current SAB kits. However, some unrepresented alleles may contain epitopes which may generate undetectable antibodies. Further studies may be needed to investigate the potential clinical impact of these unrepresented alleles and eplets, especially in certain ethnic populations or at-risk individuals.

Immune monitoring of prevalent kidney transplant recipients using Torque Teno Virus: Protocol for a single-centre prospective cohort study.

INTRODUCTION: Kidney transplant recipients (KTRs) suffer from immunosuppression-related adverse events (iRAEs), such as infections and malignancy from chronic immunosuppression, but are also at risk of graft loss from rejection with underimmunosuppression. Biomarkers that predict both iRAEs and rejection while allowing individualisation of immunosuppression exposure are lacking. Although plasma viral DNA levels of torque teno virus (TTV), a widely prevalent, non-pathogenic virus, have been shown to predict both iRAE and rejection in newly transplanted KTRs within the first year after transplant, its role for prevalent KTRs on stable immunosuppression is less clear.This study aims to determine the prognostic value of TTV levels for severe infections (defined as infections requiring hospitalisation) in prevalent KTRs on stable immunosuppression for at least 3 months and compare it against that of other commonly available biomarkers. The study also aims to explore the relationship between TTV levels and factors affecting the 'net state of immunosuppression' as well as other clinical outcomes. METHODS AND ANALYSIS: This is a single-centre, prospective, observational cohort study of 172 KTRs on stable immunosuppression for more than 3 months. TTV levels will be measured using the TTV R-GENE kit upon recruitment when study subjects are admitted and when kidney allograft biopsies are performed. Subjects will be monitored for iRAEs and rejection for at least 12 months. The relationship between TTV load and clinical outcomes such as severe infections will be analysed and compared against that from other common biomarkers and previously published predictive scores. ETHICS AND DISSEMINATION: The study was approved by the SingHealth Centralised Institutional Review Board (2023/2170). The results will be presented at conferences and submitted for publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT05836636.

Safely navigating kidney transplantation during the COVID-19 pandemic: the Singapore General Hospital's experience.

Background: The coronavirus disease 2019 (COVID-19) pandemic curtailed transplant activities worldwide, driven by concerns about increased COVID-19-related mortality among kidney transplant recipients (KTRs), infections originating from donors, and decreased availability of surgical and intensive care resources as healthcare resources are reallocated for pandemic response. We examined the outcomes of KTRs at our center before and during the COVID-19 pandemic. Methods: We conducted a retrospective single-center cohort study examining the characteristics and outcomes of patients undergoing kidney transplantation during two periods January 1, 2017 to December 31, 2019 (pre-COVID-19 era) and January 1, 2020 to June 30, 2022 (COVID-19 era). We reviewed perioperative and COVID-19 infection-related outcomes in both groups. Results: A total of 114 transplants were performed during the pre-COVID-19 era, while 74 transplants were conducted during the COVID-19 era. No differences in baseline demographics were observed. Additionally, there were no significant differences in perioperative outcomes, except for a longer cold ischemia time during the COVID-19 era. However, this did not result in an increased incidence of delayed graft function. Among the KTRs infected with COVID-19 during the pandemic era, no severe complications such as pneumonia, acute kidney injury, or death were reported. Conclusions: With the global transition to an endemic phase of COVID-19, it is imperative to revitalize organ transplant activities. Effective containment workflow, good vaccination uptake, and prompt COVID-19 treatment are essential to ensure that transplants can proceed safely.

Knowledge of COVID-19 and associated factors among kidney transplant recipients and donors in Singapore.

Background: Effective interventions during the coronavirus disease 2019 (COVID-19) pandemic require an understanding of patients' knowledge and perceptions that influence their behaviour. Our study assessed knowledge of COVID-19 among kidney transplant recipients and donors, hitherto unevaluated. Methods: We conducted a cross-sectional survey among 325 kidney transplant recipients and 172 donors between 1 May 2020 and 30 June 2020. The survey questionnaire assessed knowledge levels of COVID-19, sociodemographic data, health status, psychosocial impact of COVID-19 and precautionary behaviours during the pandemic. Results: The mean COVID-19 knowledge score of the study population was 7.5 (standard deviation: 2.2) out of 10. The mean score was significantly higher among kidney recipients compared to kidney donors (7.9 [1.9] vs. 6.7 [2.6]; P <0.001). Younger age (21-49 vs. ≥50 years) and higher education (diploma and higher vs. secondary and lower) were associated with significantly higher knowledge scores in donors, but not among recipients (P-interactions ≤0.01). In both kidney recipients and donors, financial concerns and/or social isolation were associated with lower knowledge levels. Conclusions: Concerted efforts are needed to improve COVID-19 knowledge in kidney transplant recipients and donors, particularly older donors, donors with lower education and patients with financial concerns or feelings of social isolation. Intensive patient education may mitigate the impact of education levels on COVID-19 knowledge levels.

COVID-19 vaccine acceptance among kidney transplant recipients in Singapore.

Introduction: A successful vaccination programme forms the cornerstone of controlling coronavirus disease 2019 (COVID-19). The unprecedented speed of COVID-19 vaccine development and lack of long-term data have raised fears regarding its safety and efficacy. Vaccine hesitancy can undermine the uptake, and hence success of the vaccination programme. Given the high complication rates of COVID-19 infections in kidney transplant recipients, it is particularly important to identify and address vaccine hesitancy in this population. Methods: We conducted a cross-sectional survey among kidney transplant recipients attending transplant clinic between 5 April and 5 May 2021. The survey assessed attitudes towards COVID-19, willingness/hesitancy towards COVID-19 vaccination, vaccination concerns and prompts to vaccination. This was scored on a Likert scale with scores ranging from 'strongly disagree' - 1 point to 'strongly agree' - 5 points. Results: One hundred and one completed responses were captured. Of these, 86% respondents reported to agree or strongly agree to vaccination. This was despite significant concerns of allograft rejection (mean score 4.12, standard deviation [SD] 0.97) and decreased immunosuppressant efficacy (mean score 4.14, SD 0.96) with vaccination. Multivariable model showed a positive association with transplant vintage of ≥ 5 years (median 2.41), lower educational levels of secondary school or less (median 5.82) and healthcare provider advocacy (median 1.88) in predicting vaccine acceptance. Conclusions: Vaccine acceptance rate was high among kidney transplant recipients. Vaccine hesitancy remains a concern in those with a transplant vintage of less than 5 years and those with tertiary educational level. Healthcare provider advocacy is important in improving vaccine acceptance rates.

An outpatient model of care for COVID-19 infected kidney transplant patients - The hospital-at-home.

BACKGROUND: The COVID-19 pandemic is protracted and episodic surges from viral variants continue to place significant strain on healthcare systems. COVID-19 vaccines, antiviral therapy and monoclonal antibodies have significantly reduced COVID-19 associated morbidity and mortality. Concurrently, telemedicine has gained acceptance as a model of care and a tool for remote monitoring. These advances allow us to safely transit our inpatient-based care for COVID-19 infected kidney transplant recipients (KTRs) to a hospital-at-home (HaH) model of care. METHODS: KTRs with PCR-proven COVID-19 infection were triaged by teleconsult and laboratory tests. Suitable patients were enrolled into the HaH. Remote monitoring via teleconsults were conducted daily until patients were de-isolated based on a time-based criterion. Monoclonal antibodies were administered in a dedicated clinic where indicated. RESULTS: Eighty-one KTRs with COVID-19 were enrolled into the HaH between February and June 2022, 70 (86.4%) completed HaH recovery without complications. Eleven (13.6%) patients required inpatient hospitalization for medical issues (n = 8) and weekend monoclonal antibody infusion (n = 3). Patients requiring inpatient hospitalization had longer transplant vintage (15 years vs. 10 years, p = .03), anaemia (haemoglobin 11.6 g/dL vs. 13.1 g/dL, p = .01), lower eGFR (39.8 vs. 62.9 mL/min/1.73 m2 , p < .05) and lower RBD levels (<50 AU/mL vs. 1435 AU/mL, p = .02). HaH saved 753 inpatient patient-days with no deaths observed. Hospital admission rates from the HaH programme was 13.6%. Patients who required inpatient care had direct access admission without utilization of emergency department resources. CONCLUSION: Selected KTRs with COVID-19 infection can be safely managed in a HaH programme; alleviating strain on inpatient and emergency healthcare resources.

Cardiac evaluation for end-stage kidney disease patients on the transplant waitlist: a single-center cohort study.

Background: Cardiac evaluation before deceased donor kidney transplant (DDKT) remains a matter of debate. Data on Asian countries and countries with prolonged waiting times are lacking. This study aimed to assess the outcomes of patients referred for DDKT after a cardiac evaluation at an Asian tertiary transplant center. Methods: This single-center retrospective review analyzed patients who were referred for waitlist placement and underwent cardiac stress testing between January 2009 and December 2015. Patients with cardiac symptoms were excluded. The primary outcome was three-point major adverse cardiovascular events (MACE), a composite of non-fatal myocardial infarction, non-fatal stroke, and cardiovascular death. Results: Of 468 patients referred for DDKT, 198 who underwent cardiac stress testing (myocardial perfusion studies in 159 patients and stress echocardiography in 39 patients) were analyzed. MACE occurred in 20.7% of the patients over a median follow-up of 4.6 years. Cardiac stress tests were positive for ischemia in 19.7% of the patients. Coronary angiography was performed in 63 patients, including 29 patients with diabetic kidney disease and negative cardiac stress tests. Significant coronary artery disease (CAD) was detected in 27 patients (42.8%), of whom 18 underwent revascularization. MACE was associated with significant CAD on coronary angiography in the multivariable analysis. Cardiac stress test results were not associated with MACE. Amongst diabetic patients who had negative cardiac stress tests, 37.9% had significant CAD on coronary angiography. Conclusions: The cardiovascular disease burden is significant amongst DDKT waitlist candidates. Pretransplant cardiac screening may identify patients with significant CAD at higher risk of MACE.

Psychological distress and associated factors among kidney transplant recipients and living kidney donors during COVID-19.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic has caused significant psychological distress globally. Our study assessed the prevalence of psychological distress and associated factors during COVID-19 pandemic among kidney transplant recipients and kidney donors. METHODS: A cross-sectional survey of 497 participants (325 recipients and 172 donors) was conducted from 1st May to 30th June 2020 in Singapore. The survey questionnaire assessed knowledge levels of COVID-19, socio-demographic data, health status, psychosocial impact of COVID-19, and precautionary behaviors during the pandemic. Psychological distress was defined as having anxiety, depression, or stress measured by the validated Depression, Anxiety and Stress Scale-21. Linear regression analyses were used to assess factors associated with higher psychological distress. RESULTS: The prevalence of psychological distress was 14.3% (95% confidence interval: 11.5-17.6%) in the overall population; it was 12.8% (9.79-16.6%) in recipients and 13.4% (9.08-19.6%) in donors with no significant difference (P = 0.67). Younger age (21-49 vs. ≥50 years), unmarried status, non-Singapore citizen, worse health conditions, and worrying about physical and mental health were associated with higher psychological distress. Malays (versus Chinese), taking precautionary measures (hand sanitization), and receiving enough information about COVID-19 were associated with lower psychological distress. No interactions were observed between recipients and donors. CONCLUSIONS: At least one in ten recipients and donors suffer from psychological distress during COVID-19 pandemic. Focused health education to younger adults, unmarried individuals, non-Singapore citizens, and those with poor health status could potentially prevent psychological distress in recipients and donors.