Graph-based homogenisation for modelling cardiac fibrosis.

Fibrosis, the excess of extracellular matrix, can affect, and even block, propagation of action potential in cardiac tissue. This can result in deleterious effects on heart function, but the nature and severity of these effects depend strongly on the localisation of fibrosis and its by-products in cardiac tissue, such as collagen scar formation. Computer simulation is an important means of understanding the complex effects of fibrosis on activation patterns in the heart, but concerns of computational cost place restrictions on the spatial resolution of these simulations. In this work, we present a novel numerical homogenisation technique that uses both Eikonal and graph approaches to allow fine-scale heterogeneities in conductivity to be incorporated into a coarser mesh. Homogenisation achieves this by deriving effective conductivity tensors so that a coarser mesh can then be used for numerical simulation. By taking a graph-based approach, our homogenisation technique functions naturally on irregular grids and does not rely upon any assumptions of periodicity, even implicitly. We present results of action potential propagation through fibrotic tissue in two dimensions that show the graph-based homogenisation technique is an accurate and effective way to capture fine-scale domain information on coarser meshes in the context of sharp-fronted travelling waves of activation. As test problems, we consider excitation propagation in tissue with diffuse fibrosis and through a tunnel-like structure designed to test homogenisation, interaction of an excitation wave with a scar region, and functional re-entry.

A Systematic Review of Cost-Effectiveness Studies Reporting Cost-per-DALY Averted.

INTRODUCTION: Calculating the cost per disability-adjusted life years (DALYs) averted associated with interventions is an increasing popular means of assessing the cost-effectiveness of strategies to improve population health. However, there has been no systematic attempt to characterize the literature and its evolution. METHODS: We conducted a systematic review of cost-effectiveness studies reporting cost-per-DALY averted from 2000 through 2015. We developed the Global Health Cost-Effectiveness Analysis (GHCEA) Registry, a repository of English-language cost-per-DALY averted studies indexed in PubMed. To identify candidate studies, we searched PubMed for articles with titles or abstracts containing the phrases "disability-adjusted" or "DALY". Two reviewers with training in health economics independently reviewed each article selected in our abstract review, gathering information using a standardized data collection form. We summarized descriptive characteristics on study methodology: e.g., intervention type, country of study, study funder, study perspective, along with methodological and reporting practices over two time periods: 2000-2009 and 2010-2015. We analyzed the types of costs included in analyses, the study quality on a scale from 1 (low) to 7 (high), and examined the correlation between diseases researched and the burden of disease in different world regions. RESULTS: We identified 479 cost-per-DALY averted studies published from 2000 through 2015. Studies from Sub-Saharan Africa comprised the largest portion of published studies. The disease areas most commonly studied were communicable, maternal, neonatal, and nutritional disorders (67%), followed by non-communicable diseases (28%). A high proportion of studies evaluated primary prevention strategies (59%). Pharmaceutical interventions were commonly assessed (32%) followed by immunizations (28%). Adherence to good practices for conducting and reporting cost-effectiveness analysis varied considerably. Studies mainly included formal healthcare sector costs. A large number of the studies in Sub-Saharan Africa addressed high-burden conditions such as HIV/AIDS, tuberculosis, neglected tropical diseases and malaria, and diarrhea, lower respiratory infections, meningitis, and other common infectious diseases. CONCLUSION: The Global Health Cost-Effectiveness Analysis Registry reveals a growing and diverse field of cost-per-DALY averted studies. However, study methods and reporting practices have varied substantially.

Lack of Cost-Effectiveness Analyses to Address Healthy People 2020 Priority Areas.

OBJECTIVES: To examine the extent to which recently published cost-utility analyses (cost-effectiveness analyses using quality-adjusted life-years to measure health benefits) have covered the leading health concerns in the US Department of Health and Human Services Healthy People 2020 report. METHODS: We examined data in the Tufts Medical Center Cost-Effectiveness Analysis Registry, a database containing 5000 published cost-utility analyses published in the MEDLINE literature through 2014. We focused on US-based cost-utility analyses published from 2011 through 2014 (n = 687). Two reviewers scanned abstracts and met for a consensus on categorization of cost-utility analyses that addressed the specific priorities listed in the 12 Healthy People 2020 areas (n = 120). RESULTS: Although 7.3% of recently published cost-utility analyses addressed key clinical preventive services, only about 2% of recently published cost-utility analyses covered each of the following Healthy People 2020 topics: reproductive and sexual health, nutrition/physical activity/obesity, maternal and infant health, and tobacco. Fewer than 1% addressed priorities such as injuries and violence, mental health or substance abuse, environmental quality, and oral health. CONCLUSIONS: Few cost-utility analyses have addressed Healthy People 2020 priority areas.