Asymmetric radiation-induced toroidal flow and improved confinement in tokamaks

The role of impurity radiation in influencing the toroidal flow and radial electric fields (parameters critical for determining turbulent transport) has been studied on the edge of a tokamak plasma. It is demonstrated for the first time that the impurities distributed in an asymmetric (poloidally) manner may lead to significant density and temperature perturbations on magnetic surfaces. These, in turn, interact with the θ dependent toroidal field variations and yield a mean divergence of the stress tensor driving strong neoclassical toroidal flows. A self-consistent theory of interplay of equilibrium, fluctuations, neoclassical flows, and E→×B→ shear rotation in a tokamak is also presented. It is shown that the resulting enhanced toroidal velocity shear on the outer radiative layers produces a stabilizing effect on the well known instabilities (which determine edge transport) such as the drift resistive ballooning mode, the drift trapped electron mode, and the ion temperature gradient mode. For various values of the radiation asymmetry parameter, investigation of the turbulent particle flux as a function of the density gradient shows that the plasma can undergo a bifurcation into a better-confined state with a peaked density

The Role of Expert Opinion in Projecting Long-Term Survival Outcomes Beyond the Horizon of a Clinical Trial

INTRODUCTION: Clinical trials often have short follow-ups, and long-term outcomes such as survival must be extrapolated. Current extrapolation methods often produce a wide range of survival values. To minimize uncertainty in projections, we developed a novel method that incorporates formally elicited expert opinion in a Bayesian analysis and used it to extrapolate survival in the placebo arm of DAPA-CKD, a phase 3 trial of dapagliflozin in patients with chronic kidney disease (NCT03036150). METHODS: A summary of mortality data from 13 studies that included DAPA-CKD-like populations and training on elicitation were provided to six experts. An elicitation survey was used to gather the experts' 10- and 20-year survival estimates for patients in the placebo arm of DAPA-CKD. These estimates were combined with DAPA-CKD mortality and general population mortality (GPM) data in a Bayesian analysis to extrapolate long-term survival using seven parametric distributions. Results were compared with those from standard frequentist approaches (with and without GPM data) that do not incorporate expert opinion. RESULTS: The group expert-elicited estimate for 20-year survival was 31% (lower estimate, 10%; upper estimate, 40%). In the Bayesian analysis, the 20-year extrapolated survival across the seven distributions was 14.9-39.1%, a range that was 2.4- and 1.6-fold smaller than those produced by the frequentist methods (0.0-56.9% without and 0.0-39.2% with GPM data). CONCLUSIONS: Using expert opinion in a Bayesian analysis provided a robust method for extrapolating long-term survival in the placebo arm of DAPA-CKD. The method could be applied to other populations with limited survival data

Accounting for the competing risk of death to predict kidney failure in adults with stage 4 chronic kidney disease

IMPORTANCE Kidney failure risk prediction has implications for disease management, including advance care planning in adults with severe (ie, estimated glomerular filtration rate [eGFR] category 4, [G4]) chronic kidney disease (G4-CKD). Existing prediction tools do not account for the competing risk of death.OBJECTIVE To compare predictions of kidney failure (defined as estimated glomerular filtration rate [eGFR] <10 mL/min/1.73 m(2) or initiation of kidney replacement therapy) from models that do and do not account for the competing risk of death in adults with G4-CKD.DESIGN, SETTING, AND PARTICIPANTS This prognostic study linked population-based laboratory and administrative data (2002-2017) from 2 Canadian provinces (Alberta and Manitoba) to compare 3 kidney risk models: the standard Cox regression, cause-specific Cox regression, and Fine-Gray subdistribution hazard model. Participants were adults with incident G4-CKD (eGFR 15-29 mL/min/1.73 m(2)). Data analysis occurred between July and December 2020.MAIN OUTCOMES AND MEASURES The performance of kidney risk models at prespecified times and across categories of baseline characteristics, using calibration, reclassification, and discrimination (for competing risks). Predictive characteristics were age, sex, albuminuria, eGFR, diabetes, and cardiovascular disease.RESULTS The development and validation cohorts included 14 619 (7070 [48.4%] men; mean [SD] age, 74.1 [12.8] years) and 2295 (1152 [50.2] men; mean [SD] age, 71.9 [14.0] years) adults, respectively. The 3 models had comparable calibration up to 2 years from entry. Beyond 2 years, the standard Cox regression overestimated the risk of kidney failure. At 4 years, for example, risks predicted from standard Cox were 40% for people whose observed risks were less than 30%. At 2 years (risk cutoffs 10%-20%) and 5 years (risk cutoffs 15%-30%), 788 (5.4%) and 2162 (14.8%) people in the development cohort were correctly reclassified into lower- or higher-risk categories by the Fine-Gray model and incorrectly reclassified by standard Cox regression (the opposite was observed in 272 patients [1.9%] and 0 patients, respectively). In the validation cohort, 115 (5.0%) individuals and 389 (16.9%) individuals at 2 and 5 years, respectively, were correctly reclassified into lower- or higher-risk categories by the Fine-Gray model and incorrectly reclassified by the standard Cox regression; the opposite was observed in 98 (4.3%) individuals and 0 individuals, respectively. Differences in discrimination emerged at 4 to 5 years in the development cohort and at 1 to 2 years in the validation cohort (0.85 vs 0.86 and 0.78 vs 0.8, respectively). Performance differences were minimal during the entire follow-up in people at lower risk of death (ie, aged <= 65 years or without cardiovascular disease or diabetes) and greater in those with a higher risk of death. At 5 years, for example, in people aged 65 years or older, predicted risks from standard Cox were 50% where observed risks were less than 30%. Similar miscalibration was observed at 5 years in people with albuminuria greater than 30 mg/mmol, diabetes, or cardiovascular disease.CONCLUSIONS AND RELEVANCE In this study, predictions about the risk of kidney failure were minimally affected by consideration of competing risks during the first 2 years after developing G4-CKD. However, traditional methods increasingly overestimated the risk of kidney failure with longer follow-up time, especially among older patients and those with more comorbidity.Development and application of statistical models for medical scientific researc

Risk of cardiovascular events and death associated with initiation of SGLT2 inhibitors compared with DPP-4 inhibitors:an analysis from the CVD-REAL 2 multinational cohort study

Background Cardiovascular outcome trials have shown cardiovascular benefit with sodium-glucose co-transporter-2 (SGLT2) inhibitors in patients with type 2 diabetes, whereas dipeptidyl peptidase-4 (DPP-4) inhibitors have not shown an effect. We aimed to address knowledge gaps regarding the comparative effectiveness of SGLT2 inhibitor use in clinical practice (with DPP-4 inhibitor use as an active comparator) across a range of cardiovascular risks and in diverse geographical settings. Methods In this comparative cohort study, we used data from clinical practice from 13 countries in the Asia-Pacific, Middle East, European, and North American regions to assess the risk of cardiovascular events and death in adult patients with type 2 diabetes newly initiated on SGLT2 inhibitors compared with those newly initiated on DPP-4 inhibitors. De-identified health records were used to select patients who were initiated on these drug classes between Dec 1, 2012, and May 1, 2016, with follow-up until Dec 31, 2014, to Nov 30, 2017 (full range; dates varied by country). Non-parsimonious propensity scores for SGLT2 inhibitor initiation were developed for each country and patients who were initiated on an SGLT2 inhibitor were matched with those who were initiated on a DPP-4 inhibitor in a 1:1 ratio. Outcomes assessed were hospitalisation for heart failure, all-cause death, myocardial infarction, and stroke. Hazard ratios (HRs) were estimated by country and then pooled in a weighted meta-analysis. Findings Following propensity score matching, 193 124 new users of SGLT2 inhibitors and 193 124 new users of DPP-4 inhibitors were included in the study population. Participants had a mean age of 58 years (SD 12.2), 170 335 (44.1%) of 386 248 were women, and 111933 (30.1%) of 372 262 had established cardiovascular disease. Initiation of an SGLT2 inhibitor versus a DPP-4 inhibitor was associated with substantially lower risks of hospitalisation for heart failure (HR 0.69, 95% CI 0. 61-0. 77; p Interpretation In this large, international, observational study, initiation of SGLT2 inhibitors versus DPP-4 inhibitors was associated with lower risks of heart failure, death, myocardial infarction, and stroke, providing further support for the cardiovascular benefits associated with use of SGLT2 inhibitors in patients with type 2 diabetes. Copyright (C) 2020 Elsevier Ltd. All rights reserved

Bone-specific alkaline phosphatase concentrations are less variable than those of parathyroid hormone in stable hemodialysis patients

Abnormalities of bone mineral metabolism and vascular calcification are prevalent in patients with kidney failure. Clinical management is based on biochemical targets, in particular parathyroid hormone (PTH) concentrations, but this has many limitations including high biological variation. A possible alternative is bone-specific alkaline phosphatase (ALP); therefore, we evaluated the biological variation of this marker in patients undergoing hemodialysis. Bone ALP was measured in non-fasting serum samples taken twice a week over a 6-week period in 22 stable hemodialysis patients and 12 healthy volunteers. The within-individual coefficients of variance were calculated and used to derive the critical difference required to be certain that an observed change was significant. The coefficient of variance for bone ALP was significantly higher in hemodialysis patients compared to healthy individuals. Seven samples were required to estimate the homeostatic set point of bone ALP, within 10%, in a hemodialysis patient. The concentration of serial bone ALP measurements would need to change by 36% between any two measurements before it can be considered a significant change. Since the biological variation of bone ALP is less than half that reported for PTH, our study provides further support for the use of bone ALP as an alternative marker of bone mineral metabolism in the setting of chronic kidney disease–mineral and bone disorder

Money talks: moral economies of earning a living in neoliberal East Africa

Neoliberal restructuring has targeted not just the economy, but also polity, society and culture, in the name of creating capitalist market societies. The societal repercussions of neoliberal policy and reform in terms of moral economy remain understudied. This article seeks to address this gap by analysing moral economy characteristics and dynamics in neoliberalised communities, as perceived by traders in Uganda and sex workers in Kenya. The interview data reveal perceived drivers that contributed to a significant moral dominance of money, self-interest, short-termism, opportunism and pragmatism. Equally notable are a perceived (i) close interaction between political–economic and moral–economic dynamics, and (ii) significant impact of the political–economic structure on moral agency. Respondents primarily referred to material factors usually closely linked to neoliberal reform, as key drivers of local moral economies. We thus speak of a neoliberalisation of moral economies, itself part of the wider process of embedding and locking-in market society structures in the two countries. An improved political economy of moral economy can help keep track of this phenomenon

Low bone mass in microscopic colitis

<p>Abstract</p> <p>Background</p> <p>Microscopic colitis presents with similar symptoms to classic inflammatory bowel diseases. Osteoporosis is a common complication of Crohn's disease but there are no data concerning bone metabolism in microscopic colitis.</p> <p>Aims</p> <p>The aim of the present study was to evaluate bone density and metabolism in patients with microscopic colitis.</p> <p>Methods</p> <p>Fourteen patients microscopic colitis were included in the study, and 28 healthy persons and 28 age and gender matched Crohn's disease patients were enrolled as controls. Bone mineral density was measured using dual x-ray absorptiometry at the lumbar spine, femoral neck and the radius. Serum bone formation and bone resorption markers (osteocalcin and beta-crosslaps, respectively) were measured using immunoassays.</p> <p>Results</p> <p>Low bone mass was measured in 57.14% patients with microscopic colitis. Bone mineral density at the femoral neck in patients suffering from microscopic colitis and Crohn's disease was lower than in healthy controls (0.852 ± 0.165 and 0.807 ± 0.136 vs. 1.056 ± 0.126 g/cm²; p < 0.01). Bone mineral density at the non-dominant radius was decreased in microscopic colitis patients (0.565 ± 0.093 vs. 0.667 ± 0.072 g/cm²; p < 0.05) but unaffected in Crohn's disease patients (0.672 ± 0.056 g/cm²). Mean beta-crosslaps concentration was higher in microscopic colitis and Crohn's disease patients than controls (417.714 ± 250.37 and 466.071 ± 249.96 vs. 264.75 ± 138.65 pg/ml; p < 0.05). A negative correlation between beta-crosslaps concentration and the femoral and radius t-scores was evident in microscopic colitis patients.</p> <p>Conclusions</p> <p>Low bone mass is frequent in microscopic colitis, and alterations to bone metabolism are similar to those present in Crohn's disease. Therefore, microscopic colitis-associated osteopenia could be a significant problem in such patients.</p

The kidney failure risk equation:evaluation of novel input variables including eGFR estimated using the CKD-EPI 2021 equation in 59 cohorts

SIGNIFICANCE STATEMENT: The kidney failure risk equation (KFRE) uses age, sex, GFR, and urine albumin-to-creatinine ratio (ACR) to predict 2- and 5-year risk of kidney failure in populations with eGFR <60 ml/min per 1.73 m 2 . However, the CKD-EPI 2021 creatinine equation for eGFR is now recommended for use but has not been fully tested in the context of KFRE. In 59 cohorts comprising 312,424 patients with CKD, the authors assessed the predictive performance and calibration associated with the use of the CKD-EPI 2021 equation and whether additional variables and accounting for the competing risk of death improves the KFRE's performance. The KFRE generally performed well using the CKD-EPI 2021 eGFR in populations with eGFR <45 ml/min per 1.73 m 2 and was not improved by adding the 2-year prior eGFR slope and cardiovascular comorbidities. BACKGROUND: The kidney failure risk equation (KFRE) uses age, sex, GFR, and urine albumin-to-creatinine ratio (ACR) to predict kidney failure risk in people with GFR <60 ml/min per 1.73 m 2 . METHODS: Using 59 cohorts with 312,424 patients with CKD, we tested several modifications to the KFRE for their potential to improve the KFRE: using the CKD-EPI 2021 creatinine equation for eGFR, substituting 1-year average ACR for single-measure ACR and 1-year average eGFR in participants with high eGFR variability, and adding 2-year prior eGFR slope and cardiovascular comorbidities. We also assessed calibration of the KFRE in subgroups of eGFR and age before and after accounting for the competing risk of death. RESULTS: The KFRE remained accurate and well calibrated overall using the CKD-EPI 2021 eGFR equation. The other modifications did not improve KFRE performance. In subgroups of eGFR 45-59 ml/min per 1.73 m 2 and in older adults using the 5-year time horizon, the KFRE demonstrated systematic underprediction and overprediction, respectively. We developed and tested a new model with a spline term in eGFR and incorporating the competing risk of mortality, resulting in more accurate calibration in those specific subgroups but not overall. CONCLUSIONS: The original KFRE is generally accurate for eGFR <45 ml/min per 1.73 m 2 when using the CKD-EPI 2021 equation. Incorporating competing risk methodology and splines for eGFR may improve calibration in low-risk settings with longer time horizons. Including historical averages, eGFR slopes, or a competing risk design did not meaningfully alter KFRE performance in most circumstances