Assessing associations between measures of reduced glomerular filtration rate, abnormal cardiovascular risk factors, and risk of cardiovascular morbidity and mortality

End stage renal failure is associated with a massively increased risk of cardiovascular disease, and evidence suggests that this increase in risk begins early in the development of chronic kidney disease. This thesis considers the hypothesis that small reductions in glomerular filtration rate (GFR), across the population range, are associated with a clustering of cardiovascular risk factors and increased risk of cardiovascular disease and death. Existing methods to accurately measure GFR are difficult to perform and unsuitable for large studies, while GFR estimated from blood creatinine or cystatin c concentration is inaccurate.The performance of a new method of assessing GFR, in which total plasma iohexol clearance is measured using dried capillary blood spots, was examined in a crosssectional study of 81 consecutive individuals undergoing routine measurement of GFR. The new blood spot iohexol clearance (BSIC) method (using 3 blood spot samples) assessed GFR accurately compared to traditional iohexol clearance using 3 timed plasma samples (mean±standard deviation [BSIC - reference method]: 1.1±7.7 ml/min/1.73m"); prediction equations to estimate GFR from blood creatinine and cystatin c concentration performed poorly. The results were similar when 2 blood spots (2 and 4 hours) were used, but using only a single 4 hour blood spot resulted in some loss of accuracy.The feasibility of using the BSIC method when the blood spot sampling is completed by participants at home was assessed in a cross-sectional study of 111 individuals. Following a short training, 100% of participants completed satisfactory baseline samples, 97% returned 2 timed samples through the post and 90% found the procedure acceptable. However, 21% returned small or poor quality blood spots and there was statistical evidence ofrounding-up of the recorded sampling time. Among 106 participants with measurements of BSIC-GFR, GFR estimated from blood creatinine, and cystatin c concentration, one or more measures of GFR were positively correlated with blood high density lipoprotein cholesterol concentration, and were inversely correlated with blood concentrations of triglyceride, C-reactive protein, fibrinogen, and homocysteine. BSICGFR was not more strongly related to cardiovascular risk factors than GFR estimated from blood creatinine concentration (eGFR). GFR estimated from plasma cystatin c concentration was strongly related to measures of body fat, but no relationship was seen with the other GFR measures.In a meta-analysis of cohort studies assessing the relationship between eGFR and risk of death and cardiovascular events, which included 4 061 003 and 1 372 820 individuals for each outcome respectively, a 30% lower eGFR was associated with a 20-30% increase in risk of each outcome, depending on the type of study examined. However, there was significant heterogeneity between the studies. These overall results may underestimate the impact of lower eGFR among those with chronic kidney disease since, in two large studies together contributing 85% of the deaths, lower eGFR was not associated with increased risk of death until eGFR was below 60 ml/min/1.73m2. In one large study contributing 218 000 deaths, the relative risk of death associated with lower eGFR was larger at younger ages, but eGFR had greater absolute impact at older ages and among those with prior vascular disease. Because eGFR is only weakly related to measured GFR among healthy individuals, these results may underestimate the relationship between 'true' GFR and risk of death and vascular disease.This work demonstrates an association between measures of GFR and cardiovascular risk factors, and increased risk of vascular disease, although the methods used to assess GFR may have introduced bias. Large scale studies in which GFR is accurately measured are needed. Using the new BSIC method for this purpose is potentially feasible, but further work is required to ensure accuracy when the blood sampling is completed by participants themselves

Comparative algological and bacteriological examinations on biofilms developed on different substrata in a shallow soda lake

According to the European Water Framework Directives, benthic diatoms of lakes are a tool for ecological status assessment. In this study, we followed an integrative sample analysis approach, in order to find an appropriate substratum for the water qualification-oriented biomonitoring of a shallow soda lake, Lake Velencei. Six types of substrata (five artificial and one natural), i.e., andesite, granite, polycarbonate, old reed stems, Plexiglass discs and green reed, were sampled in May and in November. We analysed total alga and diatom composition, chlorophyll a content of the periphyton, surface tension and roughness of the substrata and carbon source utilisation of microbial communities. Water quality index was calculated based on diatom composition. Moreover, using a novel statistical tool, a self-organising map, we related algal composition to substratum types. Biofilms on plastic substrates deviated to a great extent from the stone and reed substrata, with regard to the parameters measured, whereas the biofilms developing on reed and stone substrata were quite similar. We conclude that for water quality monitoring purposes, sampling from green reed during springtime is not recommended, since this is the colonization time of periphyton on the newly growing reed, but it may be appropriate from the second half of the vegetation period. Stone and artificially placed old reed substrata may be appropriate for biomonitoring of shallow soda lakes in both spring and autumn since they showed in both seasons similar results regarding all measured features

Effect of a reduction in glomerular filtration rate after nephrectomy on arterial stiffness and central hemodynamics: rationale and design of the EARNEST study

Background: There is strong evidence of an association between chronic kidney disease (CKD) and cardiovascular disease. To date, however, proof that a reduction in glomerular filtration rate (GFR) is a causative factor in cardiovascular disease is lacking. Kidney donors comprise a highly screened population without risk factors such as diabetes and inflammation, which invariably confound the association between CKD and cardiovascular disease. There is strong evidence that increased arterial stiffness and left ventricular hypertrophy and fibrosis, rather than atherosclerotic disease, mediate the adverse cardiovascular effects of CKD. The expanding practice of live kidney donation provides a unique opportunity to study the cardiovascular effects of an isolated reduction in GFR in a prospective fashion. At the same time, the proposed study will address ongoing safety concerns that persist because most longitudinal outcome studies have been undertaken at single centers and compared donor cohorts with an inappropriately selected control group.<p></p> Hypotheses: The reduction in GFR accompanying uninephrectomy causes (1) a pressure-independent increase in aortic stiffness (aortic pulse wave velocity) and (2) an increase in peripheral and central blood pressure.<p></p> Methods: This is a prospective, multicenter, longitudinal, parallel group study of 440 living kidney donors and 440 healthy controls. All controls will be eligible for living kidney donation using current UK transplant criteria. Investigations will be performed at baseline and repeated at 12 months in the first instance. These include measurement of arterial stiffness using applanation tonometry to determine pulse wave velocity and pulse wave analysis, office blood pressure, 24-hour ambulatory blood pressure monitoring, and a series of biomarkers for cardiovascular and bone mineral disease.<p></p> Conclusions: These data will prove valuable by characterizing the direction of causality between cardiovascular and renal disease. This should help inform whether targeting reduced GFR alongside more traditional cardiovascular risk factors is warranted. In addition, this study will contribute important safety data on living kidney donors by providing a longitudinal assessment of well-validated surrogate markers of cardiovascular disease, namely, blood pressure and arterial stiffness. If any adverse effects are detected, these may be potentially reversed with the early introduction of targeted therapy. This should ensure that kidney donors do not come to long-term harm and thereby preserve the ongoing expansion of the living donor transplant program.<p></p&gt

Risk factors for metabolic syndrome independently predict arterial stiffness and endothelial dysfunction in patients with chronic kidney disease and minimal comorbidity

OBJECTIVE: Metabolic syndrome (MS) is common in patients with chronic kidney disease (CKD), but its contribution to arterial stiffness and endothelial dysfunction in CKD is not well defined. We hypothesized that risk factors for MS would independently predict arterial stiffness and endothelial dysfunction in CKD patients. RESEARCH DESIGN AND METHODS: Risk factors for MS, carotid-femoral pulse wave velocity (CF-PWV) and flow-mediated dilation (FMD) as measures of arterial stiffness and endothelial dysfunction, respectively, were assessed in 113 minimally comorbid CKD patients and in 23 matched control subjects. RESULTS: CF-PWV correlated with systolic blood pressure (SBP), waist circumference, and plasma glucose (r(2) = 0.25, 0.09, and 0.09; P < 0.01 for all). FMD correlated with SBP (r(2) = 0.09; P < 0.01) and waist circumference (r(2) = 0.03; P < 0.05). CF-PWV increased progressively (r(2) = 0.07; P < 0.01) with increasing number of risk factors for MS. In multiple linear regression, SBP and waist circumference were independent determinants of CF-PWV, whereas only SBP predicted FMD. CONCLUSIONS: The number of MS risk factors is an important determinant of arterial stiffness in CKD patients irrespective of the degree of renal impairment. Although BP remains the major determinant of arterial stiffness and endothelial dysfunction, waist circumference independently predicts arterial stiffness. MS risk factors, particularly abdominal girth, are potential targets for future interventional studies in patients with CKD

Casirivimab and imdevimab in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial

Background Casirivimab and imdevimab are non-competing monoclonal antibodies that bind to two different sites on the receptor binding domain of the SARS-CoV-2 spike glycoprotein, blocking viral entry into host cells. We aimed to evaluate the efficacy and safety of casirivimab and imdevimab administered in combination in patients admitted to hospital with COVID-19. Methods RECOVERY is a randomised, controlled, open-label platform trial comparing several possible treatments with usual care in patients admitted to hospital with COVID-19. 127 UK hospitals took part in the evaluation of casirivimab and imdevimab. Eligible participants were any patients aged at least 12 years admitted to hospital with clinically suspected or laboratory-confirmed SARS-CoV-2 infection. Participants were randomly assigned (1:1) to either usual standard of care alone or usual care plus casirivimab 4 g and imdevimab 4 g administered together in a single intravenous infusion. Investigators and data assessors were masked to analyses of the outcome data during the trial. The primary outcome was 28-day all-cause mortality assessed by intention to treat, first only in patients without detectable antibodies to SARS-CoV-2 infection at randomisation (ie, those who were seronegative) and then in the overall population. Safety was assessed in all participants who received casirivimab and imdevimab. The trial is registered with ISRCTN (50189673) and ClinicalTrials.gov (NCT04381936 ). Findings Between Sept 18, 2020, and May 22, 2021, 9785 patients enrolled in RECOVERY were eligible for casirivimab and imdevimab, of which 4839 were randomly assigned to casirivimab and imdevimab plus usual care and 4946 to usual care alone. 3153 (32%) of 9785 patients were seronegative, 5272 (54%) were seropositive, and 1360 (14%) had unknown baseline antibody status. 812 (8%) patients were known to have received at least one dose of a SARS-CoV-2 vaccine. In the primary efficacy population of seronegative patients, 396 (24%) of 1633 patients allocated to casirivimab and imdevimab versus 452 (30%) of 1520 patients allocated to usual care died within 28 days (rate ratio [RR] 0·79, 95% CI 0·69–0·91; p=0·0009). In an analysis of all randomly assigned patients (regardless of baseline antibody status), 943 (19%) of 4839 patients allocated to casirivimab and imdevimab versus 1029 (21%) of 4946 patients allocated to usual care died within 28 days (RR 0·94, 95% CI 0·86–1·02; p=0·14). The proportional effect of casirivimab and imdevimab on mortality differed significantly between seropositive and seronegative patients (p value for heterogeneity=0·002). There were no deaths attributed to the treatment, or meaningful between-group differences in the pre-specified safety outcomes of cause-specific mortality, cardiac arrhythmia, thrombosis, or major bleeding events. Serious adverse reactions reported in seven (<1%) participants were believed by the local investigator to be related to treatment with casirivimab and imdevimab. Interpretation In patients admitted to hospital with COVID-19, the monoclonal antibody combination of casirivimab and imdevimab reduced 28-day mortality in patients who were seronegative (and therefore had not mounted their own humoral immune response) at baseline but not in those who were seropositive at baseline. Funding UK Research and Innovation (Medical Research Council) and National Institute of Health Research

Towards an understanding of the ethics of electronic consent in clinical trials

There are good practical reasons to use electronic consent (e-consent) in randomised trials, especially when conducting large-scale clinical trials to answer population-level health research questions. However, determining ethical reasons for e-consent is not so clear and depends on a proper understanding of what e-consent means when used in clinical trials and its ethical significance. Here we focus on four features of ethical significance which give rise to a range of ethical considerations relating to e-consent and merit further focused ethics research

PCSK9 inhibition: the dawn of a new age in cholesterol lowering?

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a circulating enzyme of hepatic origin which plays a key role in low density lipoprotein (LDL) receptor turnover. Genetic studies have confirmed that those with gain-of-function PCSK9 mutations have increased PCSK9 activity, elevated LDLcholesterol levels and a severe form of familial hypercholesterolaemia, while those with variants leading to reduced PCSK9 have lower LDL-cholesterol and a reduced risk of coronary heart disease. This has led to the development of various strategies to reduce circulating PCSK9. Monoclonal antibodies to PCSK9, given every 2-4 weeks by subcutaneous injection, have been shown to reduce LDL-cholesterol by 50-60% compared to placebo with similar effects in participants with and without diabetes. PCSK9 inhibition also reduces lipoprotein(a), an atherogenic lipid particle, by around 20- 30%. Major cardiovascular outcome trials for two agents, evolocumab and alirocumab, are expected to report from 2017. These trials involve over 45,000 participants and are likely to include about 15,000 participants with diabetes. PCSK9-binding adnectins have been developed as an alternative strategy to remove circulating PCSK9. Small interfering ribonucleic acids (RNA) which target messenger RNA for PCSK9, thereby reducing hepatic production of PCSK9, are also under investigation. These agents may only need to be given by subcutaneous injection once every 4-6 months. Ongoing trials will determine whether anti-PCSK9 antibody therapy safely reduces cardiovascular risk, but high cost may limit its use. Development of cheaper PCSK9-lowering technologies than monoclonal antibodies will be necessary for large numbers of individuals to benefit from this approach to lowering cholesterol

Novel European free-living, non-diazotrophic Bradyrhizobium isolates from contrasting soils that lack nodulation and nitrogen fixation genes - a genome comparison

The slow-growing genus Bradyrhizobium is biologically important in soils, with different representatives found to perform a range of biochemical functions including photosynthesis, induction of root nodules and symbiotic nitrogen fixation and denitrification. Consequently, the role of the genus in soil ecology and biogeochemical transformations is of agricultural and environmental significance. Some isolates of Bradyrhizobium have been shown to be non-symbiotic and do not possess the ability to form nodules. Here we present the genome and gene annotations of two such free-living Bradyrhizobium isolates, named G22 and BF49, from soils with differing long-term management regimes (grassland and bare fallow respectively) in addition to carbon metabolism analysis. These Bradyrhizobium isolates are the first to be isolated and sequenced from European soil and are the first free-living Bradyrhizobium isolates, lacking both nodulation and nitrogen fixation genes, to have their genomes sequenced and assembled from cultured samples. The G22 and BF49 genomes are distinctly different with respect to size and number of genes; the grassland isolate also contains a plasmid. There are also a number of functional differences between these isolates and other published genomes, suggesting that this ubiquitous genus is extremely heterogeneous and has roles within the community not including symbiotic nitrogen fixation

Balancing the risk of major bleeding against vascular disease risk in people without atherosclerotic disease

Background and aims: In the primary prevention setting, low-dose aspirin reduces major vascular events (MVEs) by approximately 11% but increases major bleeding (MB) by 40–50%, implying that net benefit will be most evident when the MVE-to-MB ratio is >4. This study aimed to derive cross-validated risk scores for MB and MVE and use the MVE-to-MB ratio to identify groups who may derive differing net benefits from treatment. Methods: 431 167 UK Biobank participants without known atherosclerotic cardiovascular disease at baseline were followed through record linkage for incident MVEs (myocardial infarction, non-haemorrhagic stroke, transient ischaemic attack, arterial revascularisation or vascular death) and MB (gastrointestinal and intracranial bleeds with hospital admission for ≥2 days). Risk scores were derived for MVE and MB using Cox proportional hazards models with cross-validation. Ratios of observed MVE-to-MB rates were calculated across risk categories. Results: During a median follow-up of 12 years, 18 310 participants suffered an MVE and 5352 an MB. MB risk was highest among participants with frailty, prior bleeds, cancer, liver disease or renal dysfunction, with a 4.3-fold difference in risk between the highest and lowest fifths of MB risk (HR 4.3, 95% CI 3.87 to 4.77). The MVE-to-MB ratio was ≤2.6 in the highest MB risk groups and ≥4 in lower MB risk categories. Conclusions: The derived models using routinely available disease history and laboratory measurements improved distinction of the MVE-to-MB ratio compared with using conventional models for MB risk including vascular risk factors. Such models can help identify those with moderate MVE risk but low MB risk who may benefit from low-dose aspirin

ASCEND: A Study of Cardiovascular Events iN Diabetes: Characteristics of a randomized trial of aspirin and of omega-3 fatty acid supplementation in 15,480 people with diabetes

Objectives The use of aspirin for the secondary prevention of cardiovascular disease (CVD) is firmly established, and the proportional reductions in heart attacks and strokes appear to be similar in people with and without diabetes. Uncertainty remains about the role of antiplatelet treatments for primary prevention of CVD, and guidelines vary in their recommendations. It has also been hypothesised that long-term aspirin can prevent gastro-intestinal and other cancers. Observational studies suggest associations between higher intakes of omega-3 fatty acids (FA) and lower rates of CVD, but there is no large-scale randomized evidence to support using prophylactic omega-3 FA supplementation in primary prevention. ASCEND is a randomized trial assessing whether 100 mg daily aspirin safely prevents CVD and cancer in patients with diabetes without known arterial disease. It is also assessing whether supplementation with 1 g omega-3 FA daily prevents CVD. This paper describes the methods and baseline characteristics of the randomized participants. Methods and results Between 2005 and 2011, using mail-based methods, 15,480 people with diabetes were randomized to aspirin versus placebo and, in a factorial design, to omega-3 FA supplementation versus placebo. Blood and urine samples were collected to allow baseline stratification by biochemical prognostic variables (e.g. HbA1c, blood lipids). Follow-up is for a median of at least 7 years. Conclusions Demonstrating that prophylactic aspirin safely reduces the risk of CVD or cancer in the primary prevention setting, or that omega-3 FA supplementation prevents CVD, would be relevant to hundreds of millions of people worldwide who are currently not receiving such therapies. The results of ASCEND will be reported in 2018