Mushy-layer growth and convection, with application to sea ice.

Sea ice is a reactive porous medium of ice crystals and liquid brine, which is an example of a mushy layer. The phase behaviour of sea ice controls the evolving material properties and fluid transport through the porous ice, with consequences for ice growth, brine drainage from the ice to provide buoyancy fluxes for the polar oceans, and sea-ice biogeochemistry. We review work on the growth of mushy layers and convective flows driven by density gradients in the interstitial fluid. After introducing the fundamentals of mushy-layer theory, we discuss the effective thermal properties, including the impact of salt transport on mushy-layer growth. We present a simplified model for diffusively controlled growth of mushy layers with modest cooling versus the solutal freezing-point depression. For growth from a cold isothermal boundary, salt diffusion modifies mushy-layer growth by around 5-20% depending on the far-field temperature and salinity. We also review work on the onset, spatial localization and nonlinear development of convective flows in mushy layers, highlighting recent work on transient solidification and models of nonlinear convection with dissolved solid-free brine channels. Finally, future research opportunities are identified, motivated by geophysical observations of ice growth. This article is part of the theme issue 'The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets'.

Cost-effectiveness analysis of germ-line BRCA testing in women with breast cancer and cascade testing in family members of mutation carriers.

PURPOSE: To evaluate the cost-effectiveness of BRCA testing in women with breast cancer, and cascade testing in family members of BRCA mutation carriers. METHODS: A cost-effectiveness analysis was conducted using a cohort Markov model from a health-payer perspective. The model estimated the long-term benefits and costs of testing women with breast cancer who had at least a 10% pretest BRCA mutation probability, and the cascade testing of first- and second-degree relatives of women who test positive. RESULTS: Compared with no testing, BRCA testing of affected women resulted in an incremental cost per quality-adjusted life-year (QALY) gained of AU$18,900 (incremental cost AU$1,880; incremental QALY gain 0.10) with reductions of 0.04 breast and 0.01 ovarian cancer events. Testing affected women and cascade testing of family members resulted in an incremental cost per QALY gained of AU$9,500 compared with testing affected women only (incremental cost AU$665; incremental QALY gain 0.07) with additional reductions of 0.06 breast and 0.01 ovarian cancer events. CONCLUSION: BRCA testing in women with breast cancer is cost-effective and is associated with reduced risk of cancer and improved survival. Extending testing to cover family members of affected women who test positive improves cost-effectiveness beyond restricting testing to affected women only.

Supply and demand in physician markets: a panel data analysis of GP services in Australia.

To understand the trends in any physician services market it is necessary to understand the nature of both supply and demand, but few studies have jointly examined supply and demand in these markets. This study uses aggregate panel data on general practitioner (GP) services at the Statistical Local Area level in Australia spanning eight years to estimate supply and demand equations for GP services. The structural equations of the model are estimated separately using population-weighted fixed effects panel modelling with the two stage least squares formulation of the generalised method of moments approach (GMM (2SLS)). The estimated price elasticity of demand of [Formula: see text] is comparable with other studies. The direct impact of GP density on demand, while significant, proves almost immaterial in the context of near vertical supply curves. Supply changes are therefore due to shifts in the position of the curves, partly determined by a time trend. The model is validated by comparing post-panel model predictions with actual market outcomes over a period of three years and is found to provide surprisingly accurate projections over a period of significant policy change. The study confirms the need to jointly consider supply and demand in exploring the behaviour of physician services markets.

Preventing bacterial disease in poultry in the post-antibiotic era: a case for innate immunity modulation as an alternative to antibiotic use.

The widespread use of antibiotics in the poultry industry has led to the emergence of antibiotic-resistant bacteria, which pose a significant health risk to humans and animals. These public health concerns, which have led to legislation limiting antibiotic use in animals, drive the need to find alternative strategies for controlling and treating bacterial infections. Modulation of the avian innate immune system using immunostimulatory compounds provides a promising solution to enhance poultry immune responses to a broad range of bacterial infections without the risk of generating antibiotic resistance. An array of immunomodulatory compounds have been investigated for their impact on poultry performance and immune responses. However, further research is required to identify compounds capable of controlling bacterial infections without detrimentally affecting bird performance. It is also crucial to determine the safety and effectiveness of these compounds in conjunction with poultry vaccines. This review provides an overview of the various immune modulators known to enhance innate immunity against avian bacterial pathogens in chickens, and describes the mechanisms involved.

Non-Antibiotic Compounds Synergistically Kill Chronic Wound-Associated Bacteria and Disrupt Their Biofilms.

Chronic wounds and their treatment present a significant burden to patients and healthcare systems alike, with their management further complicated by bacterial infection. Historically, antibiotics have been deployed to prevent and treat infections, but the emergence of bacterial antimicrobial resistance and the frequent development of biofilms within the wound area necessitates the identification of novel treatment strategies for use within infected chronic wounds. Here, several non-antibiotic compounds, polyhexamethylene biguanide (PHMB), curcumin, retinol, polysorbate 40, ethanol, and D-α-tocopheryl polyethylene glycol succinate 1000 (TPGS) were screened for their antibacterial and antibiofilm capabilities. The minimum inhibitory concentration (MIC) and crystal violet (CV) biofilm clearance against two bacteria frequently associated with infected chronic wounds, Staphylococcus aureus and Pseudomonas aeruginosa, were determined. PHMB was observed to have highly effective antibacterial activity against both bacteria, but its ability to disperse biofilms at MIC levels was variable. Meanwhile, TPGS had limited inhibitory activity but demonstrated potent antibiofilm properties. The subsequent combination of these two compounds in a formulation resulted in a synergistic enhancement of their capability to kill both S. aureus and P. aeruginosa and disperse their biofilms. Collectively, this work highlights the utility of combinatory approaches to the treatment of infected chronic wounds where bacterial colonization and biofilm formation remains significant issues.

Wnt/ß-catenin pathway regulates bone morphogenetic protein (BMP2)-mediated differentiation of dental follicle cells.

BACKGROUND AND OBJECTIVE: Bone morphogenetic protein 2 (BMP2)-induced osteogenic differentiation has been shown to occur through the canonical Wnt/ßcatenin pathway, whereas factors promoting canonical Wnt signaling in cementoblasts inhibit cell differentiation and promote cell proliferation in vitro. The aim of this study was to investigate whether putative precursor cells of cementoblasts, dental follicle cells (murine SVF4 cells), when stimulated with BMP2, would exhibit changes in genes/proteins associated with the Wnt/ß-catenin pathway. MATERIAL AND METHODS: SVF4 cells were stimulated with BMP2, and the following assays were carried out: (i) Wnt/ß-catenin pathway activation assessed by western blotting, ß-catenin/transcription factor (TCF) reporter assays and expression of the lymphoid enhancer-binding factor-1 (Lef1), transcription factor 7 (Tcf7), Wnt inhibitor factor 1 (Wif1) and Axin2 (Axin2) genes; and (ii) cementoblast/osteoblast differentiation assessed by mineralization in vitro, and by the mRNA levels of runt-related transcription factor 2 (Runx2), osterix (Osx), alkaline phosphatase (Alp), osteocalcin (Ocn) and bone sialoprotein (Bsp), determined by quantitative PCR after treatment with wingless-type MMTV integration site family, member 3A (WNT3A) and knockdown of ß-catenin. RESULTS: WNT3A induced ß-catenin nuclear translocation and up-regulated the transcriptional activity of a canonical Wnt-responsive reporter, suggesting that the Wnt/ß-catenin pathway functions in SVF4 cells. Activation of Wnt signaling with WNT3A suppressed BMP2-mediated induction of cementoblast/osteoblast maturation of SVF4 cells. However, ß-catenin knockdown showed that the BMP2-induced expression of cementoblast/osteoblast differentiation markers requires endogenous ß-catenin. WNT3A down-regulated transcripts for Runx2, Alp and Ocn in SVF4 cells compared with untreated cells. In contrast, BMP2 induction of Bsp transcripts occurred independently of Wnt/ß-catenin signaling. CONCLUSION: These data suggest that stabilization of ß-catenin by WNT3A inhibits BMP2-mediated induction of cementoblast/osteoblast differentiation in SVF4 cells, although BMP2 requires endogenous Wnt/ß-catenin signaling to promote cell maturation.

Inequalities in bariatric surgery in Australia: findings from 49,364 obese participants in a prospective cohort study.

OBJECTIVES: To investigate variation, and quantify socioeconomic inequalities, in the uptake of primary bariatric surgery in an obese population. DESIGN, SETTING AND PARTICIPANTS: Prospective population-based cohort study of 49,364 individuals aged 45-74 years with body mass index (BMI)≥30 kg/m2. Data from questionnaires (distributed from 1 January 2006 to 31 December 2008) were linked to hospital and death data to 30 June 2010. The sample was drawn from the 45 and Up Study (approximately 10% of New South Wales population aged 45 included, response rate approximately 18%). MAIN OUTCOME MEASURES: Rates of bariatric surgery and adjusted rate ratios (RRs) in relation to health and sociodemographic characteristics. RESULTS: Over 111,757 person-years (py) of follow-up, 312 participants had bariatric surgery, a rate of 27.92 per 10,000 py (95% CI, 24.91-31.19). Rates were highest in women, those living in major cities and those with diabetes, and increased significantly with a higher BMI and number of chronic health conditions. Adjusted RRs were 5.27 (95% CI, 3.18-8.73) for those with annual household income≥ $70 000 versus those with household income<$20,000, and 4.01 (95% CI, 2.41-6.67) for those living in areas in the least disadvantaged quintile versus those in the most disadvantaged quintile. Having versus not having private health insurance (age- and sex-adjusted RR, 9.25; 95% CI, 5.70-15.00) partially explained the observed inequalities. CONCLUSIONS: Bariatric surgery has been shown to be cost-effective in treating severe obesity and associated illnesses. While bariatric surgery rates in Australia are higher in those with health problems, large socioeconomic inequalities are apparent. Our findings suggest these procedures are largely available to those who can afford private health insurance and associated out-of-pocket costs, with poor access in populations who are most in need. Continuing inequalities in access are likely to exacerbate existing inequalities in obesity and related health problems.

Early tetrapod cranial evolution is characterized by increased complexity, constraint, and an offset from fin-limb evolution.

The developmental underpinnings and functional consequences of modifications to the limbs during the origin of the tetrapod body plan are increasingly well characterized, but less is understood about the evolution of the tetrapod skull. Decrease in skull bone number has been hypothesized to promote morphological and functional diversification in vertebrate clades, but its impact during the initial rise of tetrapods is unknown. Here, we test this by quantifying topological changes to cranial anatomy in fossil and living taxa bracketing the fin-to-limb transition using anatomical network analysis. We find that bone loss across the origin of tetrapods is associated not only with increased complexity of bone-to-bone contacts but also with decreasing topological diversity throughout the late Paleozoic, which may be related to developmental and/or mechanical constraints. We also uncover a 10-Ma offset between fin-limb and cranial morphological evolution, suggesting that different evolutionary drivers affected these features during the origin of tetrapods.

Environmentally Acquired Bacillus and Their Role in C. difficile Colonization Resistance.

Clostridioides difficile is an environmentally acquired, anaerobic, spore-forming bacterium which ordinarily causes disease following antibiotic-mediated dysbiosis of the intestinal microbiota. Although much is understood regarding the life cycle of C. difficile, the fate of C. difficile spores upon ingestion remains unclear, and the underlying factors that predispose an individual to colonization and subsequent development of C. difficile infection (CDI) are not fully understood. Here, we show that Bacillus, a ubiquitous and environmentally acquired, spore-forming bacterium is associated with colonization resistance to C. difficile. Using animal models, we first provide evidence that animals housed under conditions that mimic reduced environmental exposure have an increased susceptibility to CDI, correlating with a loss in Bacillus. Lipopeptide micelles (~10 nm) produced by some Bacilli isolated from the gastro-intestinal (GI)-tract and shown to have potent inhibitory activity to C. difficile have recently been reported. We show here that these micelles, that we refer to as heterogenous lipopeptide lytic micelles (HELMs), act synergistically with components present in the small intestine to augment inhibitory activity against C. difficile. Finally, we show that provision of HELM-producing Bacillus to microbiota-depleted animals suppresses C. difficile colonization thereby demonstrating the significant role played by Bacillus in colonization resistance. In the wider context, our study further demonstrates the importance of environmental microbes on susceptibility to pathogen colonization.

Micellar Antibiotics of Bacillus.

Members of the Bacillus genus, particularly the "Bacillus subtilis group", are known to produce amphipathic lipopeptides with biosurfactant activity. This includes the surfactins, fengycins and iturins that have been associated with antibacterial, antifungal, and anti-viral properties. We have screened a large collection of Bacillus, isolated from human, animal, estuarine water and soil samples and found that the most potent lipopeptide producers are members of the species Bacillus velezensis. B. velezensis lipopeptides exhibited anti-bacterial activity which was localised on the surface of both vegetative cells and spores. Interestingly, lipopeptide micelles (6-10 nm diameter) were detectable in strains exhibiting the highest levels of activity. Micelles were stable (heat and gastric stable) and shown to entrap other antimicrobials produced by the host bacterium (exampled here was the dipeptide antibiotic chlorotetaine). Commercially acquired lipopeptides did not exhibit similar levels of inhibitory activity and we suspect that micelle formation may relate to the particular isomeric forms produced by individual bacteria. Using naturally produced micelle formulations we demonstrated that they could entrap antimicrobial compounds (e.g., clindamycin, vancomycin and resveratrol). Micellar incorporation of antibiotics increased activity. Bacillus is a prolific producer of antimicrobials, and this phenomenon could be exploited naturally to augment antimicrobial activity. From an applied perspective, the ability to readily produce Bacillus micelles and formulate with drugs enables a possible strategy for enhanced drug delivery.

Twenty-year trends in the incidence and prevalence of diagnosed anogenital warts in Canada.

BACKGROUND: A vaccine has recently been licensed in many countries that protects against the human papillomavirus types 6, 11, 16, and 18. Types 6 and 11 account for approximately 90% of anogenital warts (AGWs). We describe the 20-year trends in the incidence and prevalence of AGWs in Manitoba, Canada. METHODS: We used linked population-based hospital and physician databases for Manitoba for 1984 to 2004. Cases were identified using tariff (billing) and ICD codes. A case was considered to be incident if it was preceded by a 12-month interval free period of AGWs care. Otherwise, it was deemed to be prevalent. An episode was considered over once a 12-month interval had elapsed without an AGW claim. RESULTS: Approximately 25,000 Manitobans were diagnosed with AGWs between 1985 and 2004. The annual age-standardized incidence rates peaked in 1992 (men, 149.9/100,000; women 170.8/100,000). In recent years, the rates have been increasing again, particularly for men. The male:female incidence rate ratio increased from 0.76 in 1985 to 1.25 in 2004. The highest incidence rate tended to be in those aged 20 to 24 years. Trends in prevalence were similar. Prevalence in 2004 was 165.2/100,000 for men and 128.4/100,000 for women. CONCLUSIONS: These population-based findings suggest that AGWs are a substantial burden to Manitobans and that their pattern has changed over time, with incidence and prevalence becoming higher in men than women. Monitoring the future trends in AGWs will provide an early marker of the effectiveness and duration of protection of human papillomavirus vaccination at a population level.

A cost analysis of producing vaccines in developing countries.

Developing country vaccine manufacturers (DCVMs) supply over half of the vaccines used in developing country immunisation programs. Decisions by developing countries to establish vaccine manufacturing should be based on economic viability, however reliable assessments of vaccine production costs are lacking. This study aimed to quantify the cost of establishing vaccine manufacturing facilities and producing vaccines in developing countries. This study estimates vaccine production costs in developing countries based on twelve vaccines produced by eight DCVMs. The results were based on estimates of the capital and operating costs required to establish vaccine manufacturing facilities under three hypothetical scenarios of production scale and scope. Cost patterns were then compared to vaccine prices paid by countries in both industrialized and developing country markets. The cost of producing vaccines in developing countries was estimated to be on average US$ 2.18 per dose, ranging between US$ 0.98 and US$ 4.85 for different vaccine types and formulations. Vaccine costs-per-dose decrease as production scale and scope increase. Cost-per-dose is mainly driven by fixed costs, but at a scale of production over 20 million doses per year it becomes driven by variable costs. Under the three hypothetical scenarios used, costs-per-dose of vaccines produced by developing countries were around 47% lower than vaccine prices in developing-country markets and 84% lower than prices in industrialized-country markets. This study has found that local production of vaccines in developing countries exhibits both economies of scale and economies of scope. The lower costs relative to prices suggests that a producer surplus and potential profits may be attainable in both developing and developed country markets, supporting sustainable production.

A cost effectiveness study of integrated care in health services delivery: a diabetes program in Australia.

BACKGROUND: Type 2 diabetes is rapidly growing as a proportion of the disease burden in Australia as elsewhere. This study addresses the cost effectiveness of an integrated approach to assisting general practitioners (GPs) with diabetes management. This approach uses a centralized database of clinical data of an Australian Division of General Practice (a network of GPs) to co-ordinate care according to national guidelines. METHODS: Long term outcomes for patients in the program were derived using clinical parameters after 5 years of program participation, and the United Kingdom Prospective Diabetes Study (UKPDS) Outcomes Model, to project outcomes for 40 years from the time of diagnosis and from 5 years post-diagnosis. Cost information was obtained from a range of sources. While program costs are directly available, and costs of complications can be estimated from the UKPDS model, other costs are estimated by comparing costs in the Division with average costs across the state or the nation. The outcome and cost measures are used derive incremental cost-effectiveness ratios. RESULTS: The clinical data show that the program is effective in the short term, with improvement or no statistical difference in most clinical measures over 5 years. Average HbA1c levels increased by less than expected over the 5 year period. While the program is estimated to generate treatment cost savings, overall net costs are positive. However, the program led to projected improvements in expected life years and Quality Adjusted Life Expectancy (QALE), with incremental cost effectiveness ratios of $A8,106 per life-year saved and $A9,730 per year of QALE gained. CONCLUSIONS: The combination of an established model of diabetes progression and generally available data has provided an opportunity to establish robust methods of testing the cost effectiveness of a program for which a formal control group was not available. Based on this methodology, integrated health care delivery provided by a network of GPs improved health outcomes of type 2 diabetics with acceptable cost effectiveness, which suggests that similar outcomes may be obtained elsewhere.

Regional adipocyte precursors in the female rat. Influence of ovarian factors.

A flow cytometric immunofluorescence procedure utilizing a specific antibody to rat adipose tissue lipoprotein lipase (LPL) was developed to quantify differentiated and undifferentiated preadipocytes present in the adipose tissue vascular stroma. This method is highly sensitive and specific for cells capable of synthesizing LPL in significant quantities. Pubescence in female rats was associated with an increase in differentiated preadipocytes and in fat cell number with enlargement of the fat depots in the perirenal, parametrial, and the subcutaneous dorsal and femoral regions. A concomitant decline in the percentage of undifferentiated preadipocytes occurred in all but the femoral depot. Ovariectomy reduced pubertal adipose growth in the femoral and parametrial but not the dorsal or perirenal regions. Furthermore, the femoral undifferentiated preadipocyte pool was not preserved in the ovariectomized animals. Thus, ovarian factors influence the pubescence-associated regional preadipocyte differentiation and conversion to adipocytes. The femoral depot contains an ovarian-dependent infinite pool of fat cell precursors. These features could account for the association between ovarian hormones and body fat topography.

Differential impacts of health care in Australia: trend analysis of socioeconomic inequalities in avoidable mortality.

BACKGROUND: Recent avoidable mortality trends in Australia suggest that health care has made a substantial contribution to reducing mortality. This study investigates if the benefits of health care have been distributed equally by comparing declines in avoidable with non-avoidable mortality over time by socioeconomic status (SES). METHODS: We calculated avoidable and non-avoidable mortality rates in Australia by small areas for 1986, 1991, 1997 and 2002. We performed pooled cross-sectional trend analysis of indirectly standardized mortality rates by SES and year, modelling using Poisson regression with over-dispersion. Socioeconomic inequalities were quantified using the relative (RII) and slope (SII) index of inequality. RESULTS: The annual percentage decline in avoidable mortality at the higher end of the socioeconomic continuum (5.0%; 95% CI: 4.7-5.4%) was larger than at the lower end (3.5%; 3.2-3.8%), with increasing relative inequality between 1986 (RII = 1.54; 1.46-1.63) and 2002 (RII = 2.00; 1.95-2.06), greater than that in non-avoidable mortality (P = 0.036). In absolute terms, avoidable deaths fell annually by 7.4 (6.9-7.8) and 8.4 (7.9-8.9) deaths per 100 000 at the higher and lower end of the spectrum, respectively, with absolute inequality decreasing between 1986 (SII = 97.8; 87.6-107.9) and 2002 (SII = 81.5; 74.6-88.5). CONCLUSIONS: Health care has contributed to decreasing the absolute SES mortality gap. However, advantaged people have obtained a disproportionate benefit of health care, contributing to widening relative health inequalities. A universal heath care system does not guarantee equality in health-care-related outcomes.

Is there evidence for dual causation between malaria and socioeconomic status? Findings from rural Tanzania.

Malaria's relationship with socioeconomic status at the macroeconomic level has been established. This is the first study to explore this relationship at the microeconomic (household) level and estimate the direction of association. Malaria prevalence was measured by parasitemia, and household socioeconomic status was measured using an asset based index. Results from an instrumental variable probit model suggest that socioeconomic status is negatively associated with malaria parasitemia. Other variables that are significantly associated with parasitemia include age of the individual, use of a mosquito net on the night before interview, the number of people living in the household, whether the household was residing at their farm home at the time of interview, household wall construction, and the region of residence. Matching estimators indicate that malaria parasitemia is associated with reduced household socioeconomic status.

Attributes and weights in health care priority setting: A systematic review of what counts and to what extent.

In most societies resources are insufficient to provide everyone with all the health care they want. In practice, this means that some people are given priority over others. On what basis should priority be given? In this paper we are interested in the general public's views on this question. We set out to synthesis what the literature has found as a whole regarding which attributes or factors the general public think should count in priority setting and what weight they should receive. A systematic review was undertaken (in August 2014) to address these questions based on empirical studies that elicited stated preferences from the general public. Sixty four studies, applying eight methods, spanning five continents met the inclusion criteria. Discrete Choice Experiment (DCE) and Person Trade-off (PTO) were the most popular standard methods for preference elicitation, but only 34% of all studies calculated distributional weights, mainly using PTO. While there is heterogeneity, results suggest the young are favoured over the old, the more severely ill are favoured over the less severely ill, and people with self-induced illness or high socioeconomic status tend to receive lower priority. In those studies that considered health gain, larger gain is universally preferred, but at a diminishing rate. Evidence from the small number of studies that explored preferences over different components of health gain suggests life extension is favoured over quality of life enhancement; however this may be reversed at the end of life. The majority of studies that investigated end of life care found weak/no support for providing a premium for such care. The review highlights considerable heterogeneity in both methods and results. Further methodological work is needed to achieve the goal of deriving robust distributional weights for use in health care priority setting.

The relationship between body mass index and hospitalisation rates, days in hospital and costs: findings from a large prospective linked data study.

BACKGROUND: Internationally there is limited empirical evidence on the impact of overweight and obesity on health service use and costs. We estimate the burden of hospitalisation-admissions, days and costs-associated with above-normal BMI. METHODS: Population-based prospective cohort study involving 224,254 adults aged ≥45y in Australia (45 and Up Study). Baseline questionnaire data (2006-2009) were linked to hospitalisation and death records (median follow-up 3.42y) and hospital cost data. The relationships between BMI and hospital admissions and days were modelled using zero-inflated negative binomial regression; generalised gamma models were used to model costs. Analyses were stratified by sex and age (45-64, 65-79, ≥80y), and adjusted for age, area of residence, education, income, smoking, alcohol-intake and private health insurance status. Population attributable fractions were also calculated. RESULTS: There were 459,346 admissions (0.55/person-year) and 1,483,523 hospital days (1.76/person-year) during follow-up. For ages 45-64y and 65-79y, rates of admissions, days and costs increased progressively with increments of above-normal BMI. Compared to BMI 22.5-<25kg/m2, rates of admissions and days were 1.64-2.54 times higher for BMI 40-50kg/m2; costs were 1.14-1.24 times higher for BMI 27.5-<30kg/m2, rising to 1.77-2.15 times for BMI 40-50kg/m2. The BMI-hospitalisation relationship was less clear for ≥80y. We estimated that among Australians 45-79y, around 1 in every 8 admissions are attributable to overweight and obesity (2% to overweight, 11% to obesity), as are 1 in every 6 days in hospital (2%, 16%) and 1 in every 6 dollars spent on hospitalisation (3%, 14%). CONCLUSIONS: The dose-response relationship between BMI and hospital use and costs in mid-age and older Australians in the above-normal BMI range suggests even small downward shifts in BMI among these people could result in considerable reductions in their annual health care costs; whether this would result in long-term savings to the health care system is not known from this study.

Economic evaluations of screening programs: a review of methods and results.

BACKGROUND: The economics of screening is part of the broader area of the economics of prevention, and is concerned with the allocation of resources to screening activities when confronted with the problem of scarcity. ISSUES: One important aspect of the economics of screening is the economic evaluation of screening programs. Economic evaluation involves a systematic assessment of the costs and benefits of screening. RESULTS: A review of methods and results of economic evaluations of screening produces no generalizable conclusion about the economic desirability or otherwise, of screening programs. Each particular screening program must be evaluated on its merits. There is no evidence of any systematic tendency for screening programs to be more or less cost-effective than other prevention or treatment programs. Across all programs, substantial disparities have been found in cost-effectiveness. CONCLUSIONS: The challenge in the future will be to secure the re-allocations of resources necessary to maximize health gains from limited health care resources, rather than to undertake the analyses on which such re-allocations would be based.

Rating the urgency of coronary angiography: results of an expert panel process. Ontario Coronary Angiography Panel.

OBJECTIVE: To rate the urgency of coronary angiography for patients with ischemic heart disease. Ratings were made for patients with varying degrees of symptoms and noninvasive cardiac test results. DESIGN: A panel of 10 cardiologists rated 354 case scenarios which presented varying combinations of clinical factors that may affect urgency. MEASUREMENTS: The case scenarios were rated by each panelist on a waiting time scale consisting of six categories which ranged from the requirement for emergency angiography to a delay of up to three months. A seventh category represented the lack of urgent need for angiography. The contribution of each clinical factor to urgency of coronary angiography was determined. MAIN RESULTS: Symptom class as defined by a modification to the Canadian Cardiovascular Society grading scale for angina pectoris, results of exercise stress tests and results of imaging studies were the major determinants of urgency. In cases of unstable angina, rest electrocardiography is of importance. These factors explained at least 95% of the variance in the case urgency scores. There was agreement by at least five of the panelists on urgency score in 84% of cases. The assigned urgency varied from 6.7, representing no urgent need for angiography, for minimally asymptomatic angina with no positive noninvasive test results, to immediate angiography for cardiogenic shock. Other factors had minimal or negligible effects on urgency. CONCLUSIONS: The urgency of need for coronary angiography was addressed by an explicit method incorporating the judgements of a panel of expert cardiologists, permitting derivation of a scoring system for rating priority of individual patients in the face of waiting lists. These methods illustrate an approach to problems presented by procedure waiting lists.