The credibility of health economic models for health policy decision-making: the case of population screening for abdominal aortic aneurysm

<i>Objectives</i>: To review health economic models of population screening for abdominal aortic aneurysm (AAA) among elderly males and assess their credibility for informing decision-making. <i>Methods</i>: A literature review identified health economic models of ultrasound screening for AAA. For each model focussing on population screening in elderly males, model structure and input parameter values were critically appraised using published good practice guidelines for decision analytic models. <i>Results</i>: Twelve models published between 1989 and 2003 were identified. Converting costs to a common currency and base year, substantial variability in cost-effectiveness results were revealed. Appraisals carried out for the nine models focusing on population screening showed differences in their complexity, with the simpler models generating results most favourable to screening. Eight of the nine models incorporated two or more simplifying structural assumptions favouring screening; uncertainty surrounding these assumptions was not investigated by any model. Quality assessments on a small number of parameters revealed input values varied between models, methods used to identify and incorporate input data were often not described, and few sensitivity analyses were reported. <i>Conclusions</i>: Large variation exists in the cost-effectiveness results generated by AAA screening models. The substantial number of factors potentially contributing to such disparities means that reconciliation of model results is impossible. In addition, poor reporting of methods makes it difficult to identify the most plausible and thus most useful model of those developed

Colorectal Cancer Brochure Development for African Americans

Introduction: African Americans are more likely to die from colorectal cancer (CRC) than any other racial/ethnic group in the United States. Unfortunately, African Americans are also less likely to undergo screening for CRC than their White counterparts. Focus groups methodology was used to refine educational brochures designed to increase CRC screening among African Americans. Methods: Two series of focus groups were completed, with a total of seven groups and 39 participants. Six different brochures (stage-matched and culturally sensitive) designed to promote CRC screening among African Americans were evaluated. Results: All participants thought that the brochures motivated them to talk with their health care providers about screening. Cost, pain, medical mistrust and fear were identified as major barriers and the brochures were modified to address these concerns. Conclusions: Focus groups methodology with African Americans can be used to inform brochures designed to increase African Americans CRC screening that addresses their major concerns

Carbon and Sulfur Cycling in Early Paleozoic Oceans

Here, I evaluate biospheric evolution during the Ordovician using high-resolution inorganic carbon and sulfur (carbonate-associated sulfate and pyrite) isotope profiles for Early Ordovician to early Late Ordovician strata from geographically distant sections in Western Newfoundland and the Argentine Precordillera. Additionally, I present new, high-resolution U-Pb ages for volcanic ash beds within strata of the Argentine Precordillera. Carbon isotope data record subdued variation that is typical of Early- to Middle Ordovician strata worldwide. By contrast, sulfur-isotopic compositions of carbonate-associated sulfate reveal a complex signal of short-term, rhythmic variation superimposed over a longer-term signal. This short-term, rhythmic variation occurs in all sections and appears to be unrelated to lithology or depositional environment, suggesting preservation of an oceanographic signal. I interpret this signal to reflect a combination of a marine sulfate reservoir that was likely much smaller than the modern, the persistence of a substantial deep-ocean hydrogen sulfide reservoir, and the episodic oxidation of a portion of the deep-ocean euxinic reservoir. Persistent euxinia likely resulted from decreased solubility of oxygen in warmer water and/or sluggish oceanic circulation during greenhouse conditions that reduced vertical ventilation. A dramatic change in the behavior of carbonate-associated sulfate and pyrite in the Middle Ordovician is interpreted to reflect a major oceanographic event that records the initial transition from Ordovician greenhouse to icehouse states. I suggest that the initiation of downwelling of increasingly cool, oxygen-rich surface water resulted in widespread oxidation of much of the deep ocean hydrogen sulfide reservoir and concomitant limitation of marine pyrite formation. It is unknown, however, why sea surface temperatures declined through the Early to Middle Ordovician. Explosive volcanism does not appear to be a primary climate driver, based on the timing of Argentinian K-bentonite formations relative to marine records of sea surface temperature, carbon and strontium isotopic composition. Rather, long-term positive feedback between organic carbon burial rates and productivity may have increased carbon dioxide drawdown, ultimately driving a gradual decrease in sea surface temperatures in the Early to Middle Ordovician

A Normative Theory of the Information Society

Alistair S. Duff has been writing interesting works about social conceptualizations of the information society since the mid-1990s. His earlier works have examined the origins of the information society paradigm, surveyed the pre-2001 research literature related to the information society, and discussed connections between the information society and social engineering, and in 2004 he explored the need for normative analysis in information policy. One can easily trace Duff’s progress toward the presently reviewed book;the aforementioned themes of the history of the information society, social engineering,and the normative attributes of information policy are the scaffolding used to support the Rawls-Tawney approach to evaluating information policy that is the centerpiece of this new monograph

La Importancia de la Teoria en el Ambito de la Biblioteconomia

Publicaciones recientes han reconocido la necesidad de más teoría en el campo de la bibliotecología y ciencias de la información; sin embargo ha habido muy poco para fomentar la construcción de teorías u ofrecer orientación en cómo se crea la teoría de la información. Este artículo provee un ejemplo de como se puede utilizar una revisión contemplativa de la investigación existente y de la literatura para desarrollar un modelo teórico de acceso a la información, con el propósito de demostrar como otros pueden tomar pasos similares para mejorar la teoría en el campo de la bibliotecología y ciencias de la información