2,287,421 research outputs found

    Cost-Benefit Estimation of Cadaveric Kidney Transplantation, the Case of a Developing Country

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    In this paper we estimate cost savings for the health-care system and quality of life improvement for patients from an increase in the number of kidney transplants in Chile. To do so, we compare the present value of dialysis and transplantation costs and quality of life in a 20-year horizon. We used Markov models and, in addition, introduce some degree of uncertainty in the value of some of the parameters that build up the model and, using Montecarlo simulations, estimate confidence intervals for our results. Our estimates suggest that an additional kidney transplant has an expected savings value of US28,000forthehealthcaresystem.Ifqualityoflifeimprovementisalsoconsidered,expectedsavingsrisetoUS 28,000 for the health-care system. If quality of life improvement is also considered, expected savings rise to US 102,000. These results imply that, increasing donation rate by one donor per million people would turn into an estimated cost saving of US827,000peryear,ornearUS 827,000 per year, or near US 3 million per year if the effect in the quality of life is considered. These results demonstrate that kidney transplants, along with a better quality of life for patients are a cost saving decision in developing countries.Cost-benefit analysis, kidney transplantation, quality adjusted life years, markov models

    Genetic and environmental influences on sleep quality in middle‐aged men: a twin study

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    Poor sleep quality is a risk factor for a number of cognitive and physiological age-related disorders. Identifying factors underlying sleep quality are important in understanding the etiology of these age-related health disorders. We investigated the extent to which genes and the environment contribute to subjective sleep quality in middle-aged male twins using the classical twin design. We used the Pittsburgh Sleep Quality Index to measure sleep quality in 1218 middle-aged twin men from the Vietnam Era Twin Study of Aging (mean age = 55.4 years; range 51-60; 339 monozygotic twin pairs, 257 dizygotic twin pairs, 26 unpaired twins). The mean PSQI global score was 5.6 [SD = 3.6; range 0-20]. Based on univariate twin models, 34% of variability in the global PSQI score was due to additive genetic effects (heritability) and 66% was attributed to individual-specific environmental factors. Common environment did not contribute to the variability. Similarly, the heritability of poor sleep-a dichotomous measure based on the cut-off of global PSQI>5-was 31%, with no contribution of the common environment. Heritability of six of the seven PSQI component scores (subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, and daytime dysfunction) ranged from 0.15 to 0.31, whereas no genetic influences contributed to the use of sleeping medication. Additive genetic influences contribute to approximately one-third of the variability of global subjective sleep quality. Our results in middle-aged men constitute a first step towards examination of the genetic relationship between sleep and other facets of aging.Accepted manuscrip

    Regaining the FORS: optical ground-based transmission spectroscopy of the exoplanet WASP-19b with VLT+FORS2

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    In the past few years, the study of exoplanets has evolved from being pure discovery, then being more exploratory in nature and finally becoming very quantitative. In particular, transmission spectroscopy now allows the study of exoplanetary atmospheres. Such studies rely heavily on space-based or large ground-based facilities, because one needs to perform time-resolved, high signal-to-noise spectroscopy. The very recent exchange of the prisms of the FORS2 atmospheric diffraction corrector on ESO's Very Large Telescope should allow us to reach higher data quality than was ever possible before. With FORS2, we have obtained the first optical ground-based transmission spectrum of WASP-19b, with 20 nm resolution in the 550--830 nm range. For this planet, the data set represents the highest resolution transmission spectrum obtained to date. We detect large deviations from planetary atmospheric models in the transmission spectrum redwards of 790 nm, indicating either additional sources of opacity not included in the current atmospheric models for WASP-19b or additional, unexplored sources of systematics. Nonetheless, this work shows the new potential of FORS2 for studying the atmospheres of exoplanets in greater detail than has been possible so far.Comment: 7 pages, 9 figures, 3 tables. Accepted for publication in A&

    Cost-Benefit Model System of Chronic Diseases in Australia to Assess and Rank Prevention and Treatment Options

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    Chronic diseases - eg heart disease, cancer, diabetes, mental disorders - affect around 80% of older Australians, are the main causes of disability and premature death, and account for 70% of total health expenditures. Because lifestyle patterns are major risk factors, chronic disease prevention and treatment are not only of medical concern, but also of considerable social, family-level and personal interest. While this makes microsimulation approaches particularly suitable for assessing intervention costs and benefits, such approaches will need to be combined with disease-progression models if health status and treatment choices are also to be simulated. AIMS: Describe methodological and technical proposals for the development of a cost-benefit model-system. METHODS: Several chronic disease progression models are to be linked to an ‘Umbrella’ microsimulation model representing the Australian population. To project 20 years ahead, use of reweighting techniques are proposed for population projections, disease-specific predictions and for health-related projections. The model-system is to account simultaneously for Australians’ demographic, socioeconomic and health-risk-factor characteristics; progression of their health status; the number of chronic diseases (comorbidities) they accumulate over time; health-related expenditures; and changes in quality of life. Standard methods are proposed to estimate costs versus benefits of simulated policy interventions and related quality of life improvements. KEY OUTCOME: Proposal of novel methods for modelling comorbidities - a task rarely attempted, although quality of life is known to decline and health expenditures to increase well above what a linear addition of the effects of individual chronic diseases would predict.Chronic Disease, Comorbidities, Cost-Benefit Model, Australia

    BMI and all cause mortality: systematic review and non-linear dose-response meta-analysis of 230 cohort studies with 3.74 million deaths among 30.3 million participants

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     To conduct a systematic review and meta-analysis of cohort studies of body mass index (BMI) and the risk of all cause mortality, and to clarify the shape and the nadir of the dose-response curve, and the influence on the results of confounding from smoking, weight loss associated with disease, and preclinical disease. PubMed and Embase databases searched up to 23 September 2015. Cohort studies that reported adjusted risk estimates for at least three categories of BMI in relation to all cause mortality. Summary relative risks were calculated with random effects models. Non-linear associations were explored with fractional polynomial models. 230 cohort studies (207 publications) were included. The analysis of never smokers included 53 cohort studies (44 risk estimates) with >738 144 deaths and >9 976 077 participants. The analysis of all participants included 228 cohort studies (198 risk estimates) with >3 744 722 deaths among 30 233 329 participants. The summary relative risk for a 5 unit increment in BMI was 1.18 (95% confidence interval 1.15 to 1.21; I(2)=95%, n=44) among never smokers, 1.21 (1.18 to 1.25; I(2)=93%, n=25) among healthy never smokers, 1.27 (1.21 to 1.33; I(2)=89%, n=11) among healthy never smokers with exclusion of early follow-up, and 1.05 (1.04 to 1.07; I(2)=97%, n=198) among all participants. There was a J shaped dose-response relation in never smokers (Pnon-linearity <0.001), and the lowest risk was observed at BMI 23-24 in never smokers, 22-23 in healthy never smokers, and 20-22 in studies of never smokers with ≥20 years follow-up. In contrast there was a U shaped association between BMI and mortality in analyses with a greater potential for bias including all participants, current, former, or ever smokers, and in studies with a short duration of follow-up (<5 years or <10 years), or with moderate study quality scores. Overweight and obesity is associated with increased risk of all cause mortality and the nadir of the curve was observed at BMI 23-24 among never smokers, 22-23 among healthy never smokers, and 20-22 with longer durations of follow-up. The increased risk of mortality observed in underweight people could at least partly be caused by residual confounding from prediagnostic disease. Lack of exclusion of ever smokers, people with prevalent and preclinical disease, and early follow-up could bias the results towards a more U shaped association

    Exploring the Expanding Universe and Dark Energy using the Statefinder Diagnostic

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    The coming few years are likely to witness a dramatic increase in high quality Sn data as current surveys add more high redshift supernovae to their inventory and as newer and deeper supernova experiments become operational. Given the current variety in dark energy models and the expected improvement in observational data, an accurate and versatile diagnostic of dark energy is the need of the hour. This paper examines the Statefinder diagnostic in the light of the proposed SNAP satellite which is expected to observe about 2000 supernovae per year. We show that the Statefinder is versatile enough to differentiate between dark energy models as varied as the cosmological constant on the one hand, and quintessence, the Chaplygin gas and braneworld models, on the other. Using SNAP data, the Statefinder can distinguish a cosmological constant (w=1w=-1) from quintessence models with w0.9w \geq -0.9 and Chaplygin gas models with κ15\kappa \leq 15 at the 3σ3\sigma level if the value of \om is known exactly. The Statefinder gives reasonable results even when the value of \om is known to only 20\sim 20% accuracy. In this case, marginalizing over \om and assuming a fiducial LCDM model allows us to rule out quintessence with w0.85w \geq -0.85 and the Chaplygin gas with κ7\kappa \leq 7 (both at 3σ3\sigma). These constraints can be made even tighter if we use the Statefinders in conjunction with the deceleration parameter. The Statefinder is very sensitive to the total pressure exerted by all forms of matter and radiation in the universe. It can therefore differentiate between dark energy models at moderately high redshifts of z \lleq 10.Comment: 21 pages, 17 figures. Minor typos corrected to agree with version published in MNRAS. Results unchange

    Constraints on the Dark Side of the Universe and Observational Hubble Parameter Data

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    This paper is a review on the observational Hubble parameter data that have gained increasing attention in recent years for their illuminating power on the dark side of the universe --- the dark matter, dark energy, and the dark age. Currently, there are two major methods of independent observational H(z) measurement, which we summarize as the "differential age method" and the "radial BAO size method". Starting with fundamental cosmological notions such as the spacetime coordinates in an expanding universe, we present the basic principles behind the two methods. We further review the two methods in greater detail, including the source of errors. We show how the observational H(z) data presents itself as a useful tool in the study of cosmological models and parameter constraint, and we also discuss several issues associated with their applications. Finally, we point the reader to a future prospect of upcoming observation programs that will lead to some major improvements in the quality of observational H(z) data.Comment: 20 pages, 6 figures, and 1 table, uses REVTeX 4.1. Review article, accepted by Advances in Astronom

    Study of association models for determining the growth of the fleet of motor vehicles in the Metropolitan Region of Cariri, Ceará

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    The quality of life underlying the modern society can be attributed to several factors, among them, the technological and economic development experienced in recent years. Durable consumer goods are part of this modern society, such as automobiles. However, because most automobiles are powered by the combustion of fossil fuels, the emission of greenhouse gases is a worrisome environmental problem. The objective of this article is to analyze Gross Domestic Product (GDP) data, population and SELIC rate (SELIC stands for Special System of Settlement and Custody) in the period from 2001 to 2020 to evaluate the impact on the number of vehicles in the Cariri Metropolitan Region (RMC), using multivariate models. It was verified that the fleet of the RMC experienced an increase of 561.45% in the last 20 years. Three prediction models were tested and the conclusion was reached that for the next 20 years it is not sustainable to maintain the same growth already experienced, in a linear manner. Instead, the ideal is to adopt a model with growth forecast with a logarithmic function, i. e. with a stationary tendency in the long time. In a society where over 50% of vehicles are more than 10 years old, it is essential that public managers, the private initiative, the academic-scientific environment and society adopt sustainable practices and consider future scenarios to make decisions in order to preserve the environment and to ensure everyone\u27s quality of life
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