The impact of location and patency of the arteriovenous fistula on quality of life of kidney transplant recipients

BackgroundArteriovenous fistulae (AVFs) may remain patent after kidney transplantation (KTx), contributing to maladaptive cardiac remodeling. The flow in AVFs is associated with the diameter of its vessels and thus with the AVF location. The main objective of this study is to assess the influence of AVF location and its patency on the self-reported quality of life (QOL) of kidney transplant recipients (KTRs) with past history of hemodialysis.MethodsTo gain clinical data, during a scheduled visit, 353 KTRs were asked to fill out an anonymous questionnaire. From this group, 284 respondents were found eligible for analysis. The outcome was defined as prevalence of symptoms and health status, measured with the Left Ventricular Dysfunction-36 (LVD-36) Questionnaire in symptomatic patients.ResultsThe hemodialysis patients (n = 243) were divided into two groups according to AVF location, i.e., DAVF – distally located AVF – (n = 174) and PAVF – proximally located AVF – (n = 69). The proportion of patients with heart failure (HF) was higher in PAVF group (24% vs. 12%, p = 0.0482). In the multivariable regression, PAVF, serum creatinine levels, and the presence of HF or coronary artery disease (CAD) remained independent predictors of lower functional capacity. Among patients with heart disease, the presence of active AVF was independently associated with worse functional outcome (higher LVD-36 scores).ConclusionsThe influence of persistent PAVF in KTRs seems to be unfavorable, especially when coexisting with CAD or HF. Abbreviations: AVF arteriovenous fistula; BMI body mass index; CAD coronary artery disease; D-AVF distally-located arteriovenous fistula; EC exercise capacity; HD hemodialysis; HF heart failure; KTx kidney transplantation; KTR kidney transplant recipient; LVD-36 Left Ventricle Disfunction – 36; LVEF left ventricle ejection fraction; LVH left ventricle hypertrophy; NYHA New York Heart Association; P-AVF proximally located arteriovenous fistula; PD peritoneal dialysis; PRO patient-reported outcomes; QOL quality of life.     

To screen or not to screen? The development of a prediction model for aorto-iliac stenosis in kidney transplant candidates

Screening for aorto-iliac stenosis is important in kidney transplant candidates as its presence affects pre-transplantation decisions regarding side of implantation and the need for an additional vascular procedure. Reliable imaging techniques to identify this condition require contrast fluid, which can be harmful in these patients. To guide patient selection for these imaging techniques, we aimed to develop a prediction model for the presence of aorto-iliac stenosis. Patients with contrast-enhanced imaging available in the pre-transplant screening between January 1st, 2000 and December 31st, 2018 were included. A prediction model was developed using multivariable logistic regression analysis and internally validated using bootstrap resampling. Model performance was assessed with the concordance index and calibration slope. Three hundred and seventy-three patients were included, 90 patients (24.1%) had imaging-proven aorto-iliac stenosis. Our final model included age, smoking, peripheral arterial disease, coronary artery disease, a previous transplant, intermittent claudication and the presence of a femoral artery murmur. The model yielded excellent discrimination (optimism-corrected concordance index: 0.83) and calibration (optimism-corrected calibration slope: 0.91). In conclusion, this prediction model can guide the development of standardized protocols to decide which patients should receive vascular screening to identify aorto-iliac stenosis. External validation is needed before this model can be implemented in patient care.     

Risks of AKI and Major Adverse Clinical Outcomes in Patients with Severe Acute Respiratory Syndrome or Coronavirus Disease 2019

BackgroundSevere acute respiratory syndrome (SARS) and coronavirus disease 2019 (COVID-19) are closely related. The effect of AKI on the clinical outcomes of these two conditions is unclear.MethodsThis retrospective, territory-wide cohort study used an electronic public healthcare database in Hong Kong to identify patients with SARS or COVID-19 by diagnosis codes, virologic results, or both. The primary endpoint was a composite of intensive care unit admission, use of invasive mechanical ventilation, and/or death.ResultsWe identified 1670 patients with SARS and 1040 patients with COVID-19 (median ages, 41 versus 35 years, respectively). Among patients with SARS, 26% met the primary endpoint versus 5.3% of those with COVID-19. Diabetes mellitus, abnormal liver function, and AKI were factors significantly associated with the primary endpoint among patients with either SARS or COVID-19. Among patients with SARS, 7.9%, 2.1%, and 3.7% developed stage 1, stage 2, and stage 3 AKI, respectively; among those with COVID-19, 6.6%, 0.4%, and 1.1% developed stage 1, stage 2, and stage 3 AKI, respectively. In both groups, factors significantly associated with AKI included diabetes mellitus and hypertension. Among patients with AKI, those with COVID-19 had a lower rate of major adverse clinical outcomes versus patients with SARS. Renal function recovery usually occurred within 30 days after an initial AKI event.ConclusionsAKI rates were higher among patients with SARS than those with COVID-19. AKI was associated with major adverse clinical outcomes for both diseases. Patients with diabetes mellitus and abnormal liver function were also at risk of developing severe consequences after SARS and COVID-19 infection.     

Laboratory tests of renal function

The kidneys are vital organs in the management of fluid balance, waste product removal, electrolyte homeostasis, acid–base balance and endocrine function. Waste products removed by the kidney are urea, uric acid and creatinine; other foreign products with similar physiochemical properties are also excreted. Urea and uric acid are by products of protein metabolism and creatinine is generated by the metabolism of creatine compounds from muscle. The kidney regulates fluid and electrolyte balance through controlling the composition and volume of urine. In the proximal convoluted tubule and the loop of Henle, 90% of sodium, potassium, calcium and magnesium are reabsorbed. Acid–base balance is achieved by regulating the excretion of hydrogen ions and bicarbonate buffering. The kidney also has a number of endocrine functions including the production of renin and erythropoietin as well as hydroxylation of vitamin D. The kidneys receive 25% of cardiac output, generating 170–200 litres of ultrafiltrate per day. Urine output is approximately 1.5 litres per day, which is concentrated ultrafiltrate through selective reabsorption of solutes and water. In this article we will discuss tests frequently used to assess renal function.     

Substituting imputation of HLA antigens for high-resolution HLA typing: Evaluation of a multiethnic population and implications for clinical decision making in transplantation

Molecular mismatch analysis for assessment of histocompatibility in transplantation requires high-resolution HLA typing. Algorithms to “guesstimate” high-resolution from low-resolution typing exist, but their accuracy remains unknown. We converted high-resolution, sequence-based, HLA typing of 310 subjects from an ethnically heterogeneous population to low-resolution equivalents and tested the ability of the NMDP HaploStats and HLA Matchmaker programs to impute/reproduce the measured high-resolution HLA type, using the more common “winner-takes-all” approach. Only 35.6% of the HaploStats imputed HLA-A, -B, -C, -DRB1, and -DQB1 haplotypes had no mistakes, and the accuracy was significantly lower for non-Caucasians (29.1%) compared to Caucasians (45.2%) (odds ratio [OR], 0.5; 95% confidence interval [CI], 0.3-0.8; P = .004). HLA Matchmaker was not able to provide high-resolution haplotypes for 45.2% of Caucasian subjects and 63.5% of non-Caucasian subjects (P = .002). Of those with an imputed result, only 10.3% of Caucasians and 4.8% of non-Caucasians had accurate 10-allele high-resolution output. Eplet analysis revealed additional, inaccurate eplets in 37% of individuals, with 22.5% showing at least 2 additional, inaccurate eplets; incorrect eplets were more common among non-Caucasians (OR, 1.8; 95% CI, 1.1-2.9; P = .018). Given this high error rate, caution should be taken before using imputation tools for clinical or research purposes, especially for non-Caucasian individuals.