Chronic kidney disease and cardiovascular risk in six regions of the world (ISN-KDDC): a cross-sectional study

Background Chronic kidney disease is an important cause of global mortality and morbidity. Data for epidemiological features of chronic kidney disease and its risk factors are limited for low-income and middle-income countries. The International Society of Nephrology’s Kidney Disease Data Center (ISN-KDDC) aimed to assess the prevalence and awareness of chronic kidney disease and its risk factors, and to investigate the risk of cardiovascular disease, in countries of low and middle income. Methods We did a cross-sectional study in 12 countries from six world regions: Bangladesh, Bolivia, Bosnia and Herzegovina, China, Egypt, Georgia, India, Iran, Moldova, Mongolia, Nepal, and Nigeria. We analysed data from screening programmes in these countries, matching eight general and four high-risk population cohorts collected in the ISN-KDDC database. High-risk cohorts were individuals at risk of or with a diagnosis of either chronic kidney disease, hypertension, diabetes, or cardiovascular disease. Participants completed a self-report questionnaire, had their blood pressure measured, and blood and urine samples taken. We defi ned chronic kidney disease according to modifi ed KDIGO (Kidney Disease: Improving Global Outcomes) criteria; risk of cardiovascular disease development was estimated with the Framingham risk score. Findings 75 058 individuals were included in the study. The prevalence of chronic kidney disease was 14·3% (95% CI 14·0–14·5) in general populations and 36·1% (34·7–37·6) in high-risk populations. Overall awareness of chronic kidney disease was low, with 409 (6%) of 6631 individuals in general populations and 150 (10%) of 1524 participants from high-risk populations aware they had chronic kidney disease. Moreover, in the general population, 5600 (44%) of 12 751 individuals with hypertension did not know they had the disorder, and 973 (31%) of 3130 people with diabetes were unaware they had that disease. The number of participants at high risk of cardiovascular disease, according to the Framingham risk score, was underestimated compared with KDIGO guidelines. For example, all individuals with chronic kidney disease should be considered at high risk of cardiovascular disease, but the Framingham risk score detects only 23% in the general population, and only 38% in high-risk cohorts. Interpretation Prevalence of chronic kidney disease was high in general and high-risk populations from countries of low and middle income. Moreover, awareness of chronic kidney disease and other non-communicable diseases was low, and a substantial number of individuals who knew they were ill did not receive treatment. Prospective programmes with repeat testing are needed to confi rm the diagnosis of chronic kidney disease and its risk factors. Furthermore, in general, health-care workforces in countries of low and middle income need strengthening

An image-based modeling framework for patient-specific computational hemodynamics

We present a modeling framework designed for patient-specific computational hemodynamics to be performed in the context of large-scale studies. The framework takes advantage of the integration of image processing, geometric analysis and mesh generation techniques, with an accent on full automation and high-level interaction. Image segmentation is performed using implicit deformable models taking advantage of a novel approach for selective initialization of vascular branches, as well as of a strategy for the segmentation of small vessels. A robust definition of centerlines provides objective geometric criteria for the automation of surface editing and mesh generation. The framework is available as part of an open-source effort, the Vascular Modeling Toolkit, a first step towards the sharing of tools and data which will be necessary for computational hemodynamics to play a role in evidence-based medicine

Effect of Trandolapril on Regression of Retinopathy in Hypertensive Patients with Type 2 Diabetes: A Prespecified Analysis of the Benedict Trial

Background. The effect of angiotensin converting enzyme inhibitors (ACEi) on regression of retinopathy in type 2 diabetics is still ill defined. Methods. We compared the incidence of retinopathy regression in 90 hypertensive type 2 diabetics randomized to at least 3-year blinded ACEi with trandolapril (2 mg/day) or non-ACEi therapy who had preproliferative or proliferative retinopathy at baseline. Results. Over a median (interquartile range) follow-up period of 35.8 (12.4–60.7) months, retinopathy regressed in 27 patients (30.0%). Regression occurred in 18 of 42 patients (42.9%) on ACEi and in 9 of 48 (18.8%) on non-ACEi therapy (adjusted for predefined baseline covariates HR (95% CI): 2.75 (1.18–6.42), P = .0193). Concomitant treatment with or without Non-Dihydropyridine Calcium Channel Blockers (ndCCBs) did not appreciably affect the incidence of retinopathy regression. Conclusions. Unlike ndCCB, ACEi therapy may have an additional effect to that of intensified BP and metabolic control in promoting regression of diabetic retinopathy

Clinical Study Effect of Trandolapril on Regression of Retinopathy in Hypertensive Patients with Type 2 Diabetes: A Prespecified Analysis of the Benedict Trial

Background. The effect of angiotensin converting enzyme inhibitors (ACEi) on regression of retinopathy in type 2 diabetics is still ill defined. Methods. We compared the incidence of retinopathy regression in 90 hypertensive type 2 diabetics randomized to at least 3-year blinded ACEi with trandolapril (2 mg/day) or non-ACEi therapy who had preproliferative or proliferative retinopathy at baseline. Results. Over a median (interquartile range) follow-up period of 35.8 (12.4-60.7) months, retinopathy regressed in 27 patients (30.0%). Regression occurred in 18 of 42 patients (42.9%) on ACEi and in 9 of 48 (18.8%) on non-ACEi therapy (adjusted for predefined baseline covariates HR (95% CI): 2.75 (1.18-6.42), P = .0193). Concomitant treatment with or without Non-Dihydropyridine Calcium Channel Blockers (ndCCBs) did not appreciably affect the incidence of retinopathy regression. Conclusions. Unlike ndCCB, ACEi therapy may have an additional effect to that of intensified BP and metabolic control in promoting regression of diabetic retinopathy

Centerline computation and geometric analysis of branching tubular surfaces with application to blood vessel modeling

In this work we present a robust and accurate method for the computation of centerlines inside branching tubular objects starting from a piecewise linear representation of their boundary. The algorithm is based on solving the Eikonal equation on the Voronoi diagram embedded into the object, with wavefront speed inversely proportional to Voronoi ball radius values. As a result, provably accurate centerlines and maximal inscribed ball radius values along them are provided. In the same framework, a method for local surface characterization is also developed, allowing robust computation of the distance of surface points to centerlines and disclosing the relationship of surface points with centerlines. A new surface-based quantity is finally proposed, the normalized tangency deviation, which provides a scale-invariant criterion for surface characterization. The developed methods are applied to 3D models of vascular segments in the context of patient-specific anatomical characterization

Characterization of the Microflow Through 3D Synthetic Niche Microenvironments Hosted in a Millifluidic Bioreactor

Background: Development of new medicines is a lengthy process with high risk of failure since drug efficacy measured in vitro is difficult to confirm in vivo. Intended to add a new tool aiding drug discovery, the MOAB-NICHOID device was developed: a miniaturized optically accessible bioreactor (MOAB) housing the 3D engineered scaffold NICHOID. The aim of our study was to characterize the microflow through the 3D nichoid microenvironment hosted in the MOAB-NICHOID device. Methods: We used computational fluid dynamics (CFD) simulations to compute the flow field inside a very fine grid resembling the scaffold microenvironment. Results: The microflow inside the multi-array of nichoid blocks is fed and locally influenced by the mainstream flow developed in the perfusion chamber of the device. Here we have revealed a low velocity, complex flow field with secondary, backward, or local recirculation micro-flows induced by the intricate architecture of the nichoid scaffold. Conclusion: Knowledge of the microenvironment inside the 3D nichoids allows planning of cell experiments, to regulate the transport of cells towards the scaffold substrate during seeding or the spatial delivery of nutrients and oxygen which affects cell growth and viability

Disturbed flow in a patient-specific arteriovenous fistula for hemodialysis: Multidirectional and reciprocating near-wall flow patterns

Actual surgical creation of vascular access has high failure rates of which stenosis formation is a major cause. We have shown previously in idealized models of side-to-end arteriovenous fistula that disturbed flow, a near-wall haemodynamic condition characterized by low and oscillating fluid shear stress, develops in focal points that correspond closely to the sites of future stenosis. Our present study was aimed at investigating whether disturbed flow occurs in patient-specific fistulae, too. We performed an image-based computational fluid dynamics study within a realistic model of wrist side-to-end anastomosis fistula at six weeks post-surgery, with subject-specific blood rheology and boundary conditions. We then categorized disturbed flow by means of established haemodynamic wall parameters. The numerical analysis revealed laminar flow within the arterial limbs and a complex flow field in the swing segment, featuring turbulent eddies leading to high frequency oscillation of the wall shear stress vectors. Multidirectional disturbed flow developed on the anastomosis floor and on the whole swing segment. Reciprocating disturbed flow zones were found on the distal artery near the floor and on the inner wall of the swing segment. We have found that both multidirectional and reciprocating disturbed flow develops on the inner side of the swing segment in a patient-specific side-to-end fistula used for vascular access after six weeks post-operatively. This has obvious implications for elucidating the haemodynamic forces involved in the initiation of venous wall thickening in vascular access

An adaptive mesh refinement solver for large-scale simulation of biological flows

The observation that hemodynamic forces play an important role in the pathophysiology of the cardiovascular system has led to the need for characterizing in vivo hemodynamics on a patient-specific basis. However, the introduction of computational hemodynamics in clinical research contexts is bound to the availability of integrated workflows for analyses on large populations. Since such workflows must rely on automated geometry-driven mesh generation methods, the availability of robust solvers featuring adaptive mesh refinement strategies is essential to ensure that the approach can be adopted on a large scale. In this paper, we present an open-source solver for the incompressible Navier–Stokes equations based on the libMesh finite elements library, featuring adaptive mesh refinement and parallelization. The solution scheme is a second-order velocity correction in rotational form. By presenting numerical tests on benchmark cases, we demonstrate that the coupling of this solution strategy with adaptive mesh refinement leads to a solver with good accuracy characteristics despite the relative simplicity of the scheme adopted. The availability of this solver within the Vascular Modeling Toolkit project leads to a widely available, seamless pipeline from images to simulation ready to be applied in clinical research environments. Copyright © 2009 John Wiley & Sons, Ltd