Variations in statin prescribing for primary cardiovascular disease prevention: cross-sectional analysis

Background Statins are an important intervention for primary and secondary cardiovascular disease (CVD) prevention. We aimed to establish the variation in primary preventive treatment for CVD with statins in the English population. Methods Cross sectional analyses of 6155 English primary care practices with 40,017,963 patients in 2006/7. Linear regression was used to model prescribing rates of statins for primary CVD prevention as a function of IMD (index of multiple deprivation) quintile, proportion of population from an ethnic minority, and age over 65 years. Defined Daily Doses (DDD) were used to calculate the numbers of patients receiving a statin. Statin prescriptions were allocated to primary and secondary prevention based on the prevalence of CVD and stroke. Results We estimated that 10.5% (s.d.3.7%) of the registered population were dispensed a statin for any indication and that 6.3% (s.d. 3.0%) received a statin for primary CVD prevention. The regression model explained 21.2% of the variation in estimates of prescribing for primary prevention. Practices with higher prevalence of hypertension (β co-efficient 0.299 p <0.001) and diabetes (β co-efficient 0.566 p < 0.001) prescribed more statins for primary prevention. Practices with higher levels of ethnicity (β co-efficient-0.026 p <0.001), greater deprivation (β co-efficient −0.152 p < 0.001) older patients (β co-efficient −0.032 p 0.002), larger lists (β co-efficient −0.085, p < 0.001) and were more rural (β co-efficient −0.121, p0.026) prescribed fewer statins. In a small proportion of practices (0.5%) estimated prescribing rates for statins were so low that insufficient prescriptions were issued to meet the predicted secondary prevention requirements of their registered population. Conclusions Absolute estimated prescribing rates for primary prevention of CVD were 6.3% of the population. There was evidence of social inequalities in statin prescribing for primary prevention. These findings support the recent introduction of a financial incentive for primary prevention of CVD in England

Foundations and their practical implications for the constitutive coefficients of poromechanical dual-continuum models

A dual-continuum model can offer a practical approach to understanding first-order behaviours of poromechanically coupled multiscale systems. To close the governing equations, constitutive equations with models to calculate effective constitutive coefficients are required. Several coefficient models have been proposed within the literature. However, a holistic overview of the different modelling concepts is still missing. To address this we first compare and contrast the dominant models existing within the literature. In terms of the constitutive relations themselves, early relations were indirectly postulated that implicitly neglected the effect of the mechanical interaction arising between continuum pressures. Further, recent users of complete constitutive systems that include inter-continuum pressure coupling have explicitly neglected these couplings as a means of providing direct relations between composite and constituent properties, and to simplify coefficient models. Within the framework of micromechanics, we show heuristically that these explicit decouplings are in fact coincident with bounds on the effective parameters themselves. Depending on the formulation, these bounds correspond to end-member states of isostress or isostrain. We show the impacts of using constitutive coefficient models, decoupling assumptions and parameter bounds on poromechanical behaviours using analytical solutions for a 2D model problem. Based on the findings herein, we offer recommendations for how and when to use different coefficient modelling concepts.Comment: Transport in Porous Media (2019

Anisotropic dual-continuum representations for multiscale poroelastic materials:Development and numerical modelling

Dual-continuum (DC) models can be tractable alternatives to explicit approaches for the numerical modelling of multiscale materials with multiphysics behaviours. This work concerns the conceptual and numerical modelling of poroelastically coupled dual-scale materials such as naturally fractured rock. Apart from a few exceptions, previous poroelastic DC models have assumed isotropy of the constituents and the dual-material. Additionally, it is common to assume that only one continuum has intrinsic stiffness properties. Finally, little has been done into validating whether the DC paradigm can capture the global poroelastic behaviours of explicit numerical representations at the DC modelling scale. We address the aforementioned knowledge gaps in two steps. First, we utilise a homogenisation approach based on Levin's theorem to develop a previously derived anisotropic poroelastic constitutive model. Our development incorporates anisotropic intrinsic stiffness properties of both continua. This addition is in analogy to anisotropic fractured rock masses with stiff fractures. Second, we perform numerical modelling to test the dual-continuum model against fine-scale explicit equivalents. In doing, we present our hybrid numerical framework, as well as the conditions required for interpretation of the numerical results. The tests themselves progress from materials with isotropic to anisotropic mechanical and flow properties. The fine-scale simulations show anisotropy can have noticeable effects on deformation and flow behaviour. However, our numerical experiments show the DC approach can capture the global poroelastic behaviours of both isotropic and anisotropic fine-scale representations

An investigation of tin whisker growth over a 32-year period

Purpose: This paper presents the results of a 32 year old laboratory study of whisker growth from tin electrodeposits that was originally undertaken to gain an increased understanding of the phenomenon of tin whisker growth. Design/methodology/approach: Whisker growth was evaluated using electroplated C-rings (both stressed and un-stressed) that were stored throughout in a desiccator at room temperature. Analysis has recently been undertaken to evaluate whisker growth and intermetallic growth after 32 years storage. SEM analysis has been performed to investigate whisker length and, using polished cross-sections, the morphology, thickness and type of intermetallic formation. Findings: Normal tin plated deposits on brass and steel with a copper barrier layer nucleated whiskers within 5 months and in each case these grew to lengths between 1 and 4.5 mm. For normal tin electroplated onto brass, a one or two month nucleation period was needed before whiskers developed. They reached a maximum length of about 1.5 mm after 6 months and little or no further growth occurred during the subsequent 32 years. Very few whiskers grew on the tin-plated steel samples and no intermetallic formation was observed. None of the fused tin-platings nucleated whiskers during the 32 year period. Practical implications: Knowledge about vintage whiskers is important in order that we can take steps to increase the resiliency of our space missions. Similarly, such knowledge is important to engineers engaged on products reaching their nominal end-of-life, but where for reasons of economy, these products cannot be replaced Originality/value: This study represents a unique insight into whisker growth and intermetallic formation over an extremely long time period

Personalising the evaluation of substance misuse treatment: A new approach to outcome measurement

Patient involvement in healthcare, in general, and in substance misuse in particular, has become a topic of paramount importance (Rutter et al., 2004). Patient involvement can be conceptualised as listening to the patients’ perspective and encouraging patients to take an active role in the care they are receiving. This approach is advocated by international authorities in health and social care such as the United Kingdom’s NICE, which recommends “person-centred care” that takes into account the patient’s “needs, preferences and strengths” (Crawford, 2011). According to Orford (2008), the perspectives of patients in substance misuse treatment tend to be overlooked and their involvement with treatment is limite

Individualised or Standardised Outcome Measures: A Co-habitation?

Mental health outcome measurement is conflicted between two different schools of thought which underlie the division between standardised (nomothetic) and individualised or patient-generated (idiographic) measures. The underpinning philosophies of both approaches have very different starting points in terms of how we understand the world. And yet the strengths of both may contribute something useful for patients and mental health services. We suggest a convergence of approaches with new thinking on options for co-habitation

Effect of social deprivation on blood pressure monitoring and control in England: a survey of data from the quality and outcomes framework

Objective To determine levels of blood pressure monitoring and control in primary care and to determine the effect of social deprivation on these levels

Whisker Mitigation Strategies for Pb-Free Electronics

Whisker Mitigation Strategies for Pb-Free Electronic

Multiscale dual-continuum modelling of deformable porous media

Within the geosciences, we are often challenged by how to model the coupling of physical phenomena across varying space and time scales, as well as between different phenomena themselves. As a result, we forgo accuracy and physical consistency/understanding, in favour of efficiency and practicality. To address these tradeoffs we can use multiscale and multiphysics modelling. In this work, we are concerned with multiscale behaviours owing to the coupling between a microscale model and a (macroscopic) dual-continuum model. For the multiphysics component, we consider the coupling between linear deformation and flow, referred to as poroelasticity. Accordingly, the goal of this thesis is to apply multiscale and multiphysics modelling concepts to the study of strongly heterogeneous (deformable) porous media, to better understand and represent the links between various scales of interest. We split this work into three main parts. Part one investigates the relations between microscopic and dual-continuum poroelastic constitutive models, including previously introduced phenomenological models. To do so, we use micromechanical approaches. Subsequently, starting from the microscale, we derive a fully anisotropic dual-continuum poroelastic constitutive model using homogenisation. We then show how the resulting model is related to constitutive models available in literature. For these previously introduced models, we use micromechanical considerations and analytical solutions to compare and contrast the various modelling concepts used in their derivation. We also investigate various simplifying assumptions made by past users of these models. On the basis of our studies we provide recommendations for how and when to use the various dual-continuum poroelastic constitutive modelling concepts and simplifications. Part two introduces a numerical framework for poroelastic dual-continuum modelling. We subsequently use this framework to further study the links between microscale and macroscale poroelastic materials. Our numerical framework considers anisotropy and uses a hybrid discretisation suited for the flow and deformation subproblems accordingly. We benchmark the resulting framework against analytical solutions and demonstrate its use on a complex geological grid. With the framework in-hand we compare and study dual-continuum behaviours against microscale representations given various modelling and material assumptions on the latter. We present a number of tests starting from isotropic cases, progressing to more complex anisotropic cases. Our results show that anisotropy can have measurable effects on coupled behaviours. However, for the tests considered, we show the dual-continuum approach is capable of capturing the global poroelastic behaviours of microscopic representations. Finally, part three establishes a computational multiscale approach based on machine learning to improve the accuracy of macroscopic approaches in subsurface modelling. Here the idea is to use data-driven modelling as a surrogate constitutive model within a hierarchical multiscale setting. Accordingly, we detail the framework, describing the key components and considerations therein. We then apply the framework to the problem of inter-continuum mass transfer, whilst considering an uncoupled (flow only) dual-continuum representation. We couple the resulting data-driven model to a physics-based model leading to a hybrid machine learning-physics-based approach. We show the resulting hybrid method to give high quality results with respect to a microscale model, without the computational expense of the latter