Publications by authors named "James K Hammitt"

63 Publications

The Modest Effects of Fact Boxes on Cancer Screening.

J Risk Uncertain 2021 Feb 17;62(1):29-54. Epub 2021 Feb 17.

Harvard Medical School, Boston, MA, USA; Boston Children's Hospital, Boston, MA, USA.

As health care becomes increasingly personalized to the needs and values of individual patients, informational interventions that aim to inform and debias consumer decision-making are likely to become important tools. In a randomized controlled experiment, we explore the effects of providing participants with published fact boxes on the benefits and harms of common cancer screening procedures. Female participants were surveyed about breast cancer screening by mammography, while male participants were surveyed about prostate cancer screening by prostate-specific antigen (PSA) testing. For these screening procedures, we expect consumers to have overly optimistic prior beliefs about the benefits and harms. We find that participants update their beliefs about the net benefits of screening modestly, but we observe little change in their stated preferences to seek screening. Participants who scored higher on a numeracy test updated their beliefs about screening benefits more in response to the fact boxes than did participants who scored lower on the numeracy test.
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http://dx.doi.org/10.1007/s11166-021-09344-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8354090PMC
February 2021

The future costs of methane emissions.

Authors:
James K Hammitt

Nature 2021 04;592(7855):514-515

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http://dx.doi.org/10.1038/d41586-021-00972-6DOI Listing
April 2021

Introduction to Special Issue on Risk Assessment, Economic Evaluation, and Decisions.

Risk Anal 2021 04;41(4):559-564

Harvard T.H. Chan School of Public Health, Boston, MA, USA.

Integrating risk assessment, economic evaluation, and uncertainty to inform policy decisions is a core challenge to risk analysis. In September 2019, the Harvard Center for Risk Analysis, with support from the Society for Risk Analysis Economics and Benefits Analysis Specialty Group and others, convened a workshop to address this issue. The workshop built in part on the recommendations of the 2009 National Research Council report, Science and Decisions: Advancing Risk Assessment. It honored John S. Evans, whose thoughtful and innovative teaching and scholarship have significantly advanced thinking on these issues. This special issue features a profile of Dr. Evans and nine articles that build on work presented at the workshop.
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http://dx.doi.org/10.1111/risa.13720DOI Listing
April 2021

Fair innings? The utilitarian and prioritarian value of risk reduction over a whole lifetime.

J Health Econ 2021 01 30;75:102412. Epub 2020 Nov 30.

INRAE, Toulouse School of Economics, University Toulouse Capitole, France. Electronic address:

The social value of risk reduction (SVRR) is the marginal social value of reducing an individual's fatality risk, as measured by some social welfare function (SWF). This Article investigates SVRR, using a lifetime utility model in which individuals are differentiated by age, lifetime income profile, and lifetime risk profile. We consider both the utilitarian SWF and a "prioritarian" SWF, which applies a strictly increasing and strictly concave transformation to individual utility. We show that the prioritarian SVRR provides a rigorous basis in economic theory for the "fair innings" concept, proposed in the public health literature: as between an older individual and a similarly situated younger individual (one with the same income and risk profile), a risk reduction for the younger individual is accorded greater social weight even if the gains to expected lifetime utility are equal. The comparative statics of prioritarian and utilitarian SVRRs with respect to age, and to (past, present, and future) income and baseline survival probability, are significantly different from the conventional value per statistical life (VSL). Our empirical simulation based upon the U.S. population survival curve and income distribution shows that prioritarian SVRRs with a moderate degree of concavity in the transformation function conform to widely held views regarding lifesaving policies: the young should take priority but income should make no difference.
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http://dx.doi.org/10.1016/j.jhealeco.2020.102412DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7846816PMC
January 2021

Mortality Benefits and Control Costs of Improving Air Quality in Mexico City: The Case of Heavy Duty Diesel Vehicles.

Risk Anal 2021 04 24;41(4):661-677. Epub 2020 Dec 24.

Harvard TH Chan School of Public Health, Boston, MA, USA.

Diesel vehicles are significant contributors to air pollution in Mexico City. We estimate the costs and mortality benefits of retrofitting heavy-duty vehicles with particulate filters and oxidation catalysts. The feasibility and cost-effectiveness of controls differ by vehicle model-year and type. We evaluate 1985 to 2014 model-year vehicles from 10 vehicle classes and five model-year groups. Our analysis shows that retrofitting all vehicles with the control that maximizes expected net benefits for that vehicle type and model-year group has the potential to reduce emissions of primary fine particles (PM ) by 950 metric tons/year; cut the population-weighted annual mean concentration of PM in Mexico City by 0.90 µg/m ; reduce the annual number of deaths attributable to air pollution by over 80; and generate expected annual health benefits of close to 250 million US$. These benefits outweigh expected costs of 92 million US$ per year. Diesel retrofits are but one step that should viewed in the context of other efforts--such as development of an integrated public transportation system, promotion of the rational use of cars, reduction of emissions from industrial sources and fires, and redesign of the Mexico City Metropolitan Area to reduce urban sprawl--that must be analyzed and implemented to substantially control air pollution and protect public health. Even if considering other potential public health interventions, which would offer greater benefits at the same or lower costs, only by conducting, promoting, and publishing this sort of analyses, we can make strides to improve public health cost-effectively.
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http://dx.doi.org/10.1111/risa.13655DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8247320PMC
April 2021

Estimating the Potential Health Benefits of Air Quality Warnings.

Risk Anal 2021 04 29;41(4):645-660. Epub 2020 Nov 29.

Harvard Kennedy School of Government, Cambridge, MA, USA.

National, state, and local air quality authorities issue warnings urging residents to stay indoors or to take other precautions when pollutant levels are expected to exceed defined thresholds. Previous work explores the impact of warnings on specific activities but not the health improvements that might result if individuals fully responded to the recommendations. We estimate these potential health impacts using recent pollution data in three U.S. locations: Denver, Colorado; Los Angeles, California; and Pittsburgh, Pennsylvania. We focus on mortality risks among the elderly, who are particularly vulnerable. Under the strong assumptions of no infiltration and no offsetting indoor sources, we estimate that the benefits associated with avoiding ambient ozone and fine particle exposure are generally less than $14 per person for one additional hour spent indoors on days when air quality thresholds are exceeded. These estimates are sensitive to assumptions regarding the relationship between decreased exposure and mortality risks. Individuals' decisions to stay indoors likely depend on the value of the health benefits compared with the value of forgone work and leisure activities. While the national warning system provides flexibility and allows individuals to tailor their responses to personal circumstances, our analysis suggests that its benefits under typical conditions are small. The benefits of warnings under wildfire or other extreme conditions may be much greater.
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http://dx.doi.org/10.1111/risa.13640DOI Listing
April 2021

Valuing mortality risk in the time of COVID-19.

Authors:
James K Hammitt

J Risk Uncertain 2020 Nov 11:1-26. Epub 2020 Nov 11.

Harvard University (Center for Risk Analysis & Center for Health Decision Science), Cambridge, MA USA.

In evaluating the appropriate response to the COVID-19 pandemic, a key parameter is the rate of substitution between wealth and mortality risk, conventionally summarized as the value per statistical life (VSL). For the United States, VSL is estimated as approximately $10 million, which implies the value of preventing 100,000 COVID-19 deaths is $1 trillion. Is this value too large? There are reasons to think so. First, VSL is a marginal rate of substitution and the potential risk reductions are non-marginal. The standard VSL model implies the rate of substitution of wealth for risk reduction is smaller when the risk reduction is larger, but a closed-form solution calibrated to estimates of the income elasticity of VSL shows the rate of decline is modest until the value of a non-marginal risk reduction accounts for a substantial share of income; average individuals are predicted to be willing to spend more than half their income to reduce one-year mortality risk by 1 in 100. Second, mortality risk is concentrated among the elderly, for whom VSL may be smaller and who would benefit from a persistent risk reduction for a shorter period because of their shorter life expectancy. Third, the pandemic and responses to it have caused substantial losses in income that should decrease VSL. In contrast, VSL is plausibly larger for risks (like COVID-19) that are dreaded, uncertain, catastrophic, and ambiguous. These arguments are evaluated and key issues for improving estimates are highlighted.
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http://dx.doi.org/10.1007/s11166-020-09338-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7656098PMC
November 2020

Assessing the health impacts of electric vehicles through air pollution in the United States.

Environ Int 2020 11 25;144:106015. Epub 2020 Aug 25.

Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA 02115, United States.

The environmental consequences of electric vehicles (EV) have been extensively studied, but the literature on their health impacts is scant. At the same time, fine particulate matter (PM), for which transportation is a major source, remains an important public health issue in the United States. Motivated by recent developments in epidemiology and reduced-form air pollution modeling, as well as reductions in power plant emissions, we conduct an updated assessment of health benefits of light-duty vehicle electrification in large metropolitan areas (MSAs) in the United States. We first calculate MSA-specific mortality impacts per mile attributable to fine particles from internal combustion engine vehicle (ICEV) tailpipe emissions of PM, SO, NO, NH, and volatile organic compounds, and power plant emissions of PM, SO, and NO. We complement these with changes in greenhouse-gas emissions associated with vehicle electrification. We find that electrification leads to large benefits, even with EVs powered exclusively by fossil fuel plants. VMT-weighted mean benefits in the 53 MSAs are 6.9 ¢/mile ($10,400 per 150,000 miles), 83% of which (5.7 ¢/mile or $8600 per 150,000 miles) comes from reductions in PM-attributable mortality. Variability among the MSAs is large, with benefits ranging from 3.4 ¢/mile ($5100 per 150,000 miles) in Rochester, NY, to 11.5 ¢/mile ($17,200 per 150,000 miles) in New York, NY. This large variability suggests incentives should vary by MSA and presents an opportunity to target areas for EV deployment aimed at maximizing public health benefits. Impacts are smaller when EVs disproportionately replace newer ICEV models but EVs still lead to positive benefits in all MSAs. Vehicle electrification in urban areas is an opportunity to achieve large public health benefits in the United States in the short term.
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http://dx.doi.org/10.1016/j.envint.2020.106015DOI Listing
November 2020

Theoretical bounds on the value of improved health.

J Health Econ 2020 07 23;72:102341. Epub 2020 May 23.

European Chemicals Agency, Finland.

Policies that improve health and longevity are often valued by combining expected gains in quality-adjusted life years (QALYs) with a constant willingness-to-pay (WTP) per QALY. This constant is derived by dividing value per statistical life (VSL) estimates by expected future QALYs. We explore the theoretical validity of this practice by studying the properties of WTP for improved health and longevity in a framework that makes minimal assumptions about the shape of an agent's utility function. We find that dividing VSL by expected QALYs results in an upper bound on the WTP for a marginal improvement in the quality of life, as measured by gains in health status or longevity. Calibration results suggest that analysts using this approach to monetize health benefits overestimate the value of a program or policy by a factor of two on average. We also derive a lower bound on the WTP for improved health and longevity that permits a novel empirical test for the descriptive validity of the QALY model. Our calibrations suggest that this lower bound is on average 20% smaller than the actual WTP.
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http://dx.doi.org/10.1016/j.jhealeco.2020.102341DOI Listing
July 2020

Premature Deaths, Statistical Lives, and Years of Life Lost: Identification, Quantification, and Valuation of Mortality Risks.

Risk Anal 2020 Apr 10;40(4):674-695. Epub 2019 Dec 10.

University of Cologne (Institute and Policlinic for Occupational Medicine, Environmental Medicine and Prevention Research), Köln, Germany.

Mortality effects of exposure to air pollution and other environmental hazards are often described by the estimated number of "premature" or "attributable" deaths and the economic value of a reduction in exposure as the product of an estimate of "statistical lives saved" and a "value per statistical life." These terms can be misleading because the number of deaths advanced by exposure cannot be determined from mortality data alone, whether from epidemiology or randomized trials (it is not statistically identified). The fraction of deaths "attributed" to exposure is conventionally derived as the hazard fraction (R - 1)/R, where R is the relative risk of mortality between high and low exposure levels. The fraction of deaths advanced by exposure (the "etiologic" fraction) can be substantially larger or smaller: it can be as large as one and as small as 1/e (≈0.37) times the hazard fraction (if the association is causal and zero otherwise). Recent literature reveals misunderstanding about these concepts. Total life years lost in a population due to exposure can be estimated but cannot be disaggregated by age or cause of death. Economic valuation of a change in exposure-related mortality risk to a population is not affected by inability to know the fraction of deaths that are etiologic. When individuals facing larger or smaller changes in mortality risk cannot be identified, the mean change in population hazard is sufficient for valuation; otherwise, the economic value can depend on the distribution of risk reductions.
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http://dx.doi.org/10.1111/risa.13427DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7217195PMC
April 2020

What risk of death would people take to be cured of HIV and why? A survey of people living with HIV.

J Virus Erad 2019 Apr 1;5(2):109-115. Epub 2019 Apr 1.

Duke University School of Medicine, Durham, NC, USA.

People living with HIV (PLWHIV) can reasonably expect near-normal longevity, yet many express a willingness to assume significant risks to be cured. We surveyed 200 PLWHIV who were stable on antiretroviral therapy (ART) to quantify associations between the benefits they anticipate from a cure and their risk tolerance for curative treatments. Sixty-five per cent expected their health to improve if cured of HIV, 41% predicted the virus would stop responding to medications over the next 20 years and 54% predicted experiencing serious medication side effects in the next 20 years. Respondents' willingness to risk death for a cure varied widely (median 10%, 75th percentile 50%). In multivariate analyses, willingness to risk death was associated with expected long-term side effects of ART, greater financial resources and being employed (all  < 0.05) but was not associated with perceptions of how their health would improve if cured.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6543487PMC
April 2019

Conducting Benefit-Cost Analysis in Low- and Middle-Income Countries: Introduction to the Special Issue.

J Benefit Cost Anal 2019 27;10(Suppl 1):1-14. Epub 2019 Feb 27.

Damian G. Walker: Bill & Melinda Gates Foundation, 500 Fifth Avenue North, Seattle, WA 98109, USA.

Investing in global health and development requires making difficult choices about what policies to pursue and what level of resources to devote to different initiatives. Methods of economic evaluation are well established and widely used to quantify and compare the impacts of alternative investments. However, if not well conducted and clearly reported, these evaluations can lead to erroneous conclusions. Differences in analytic methods and assumptions can obscure important differences in impacts. To increase the comparability of these evaluations, improve their quality, and expand their use, this special issue includes a series of papers developed to support reference case guidance for benefit-cost analysis. In this introductory article, we discuss the background and context for this work, summarize the process we are following, describe the overall framework, and introduce the articles that follow.
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http://dx.doi.org/10.1017/bca.2019.4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7672367PMC
February 2019

Valuing Mortality Risk Reductions in Global Benefit-Cost Analysis.

J Benefit Cost Anal 2019 15;10(Suppl 1):15-50. Epub 2019 Jan 15.

Harvard T.H. Chan School of Public Health, Center for Health Decision Science and Center for Risk Analysis, 718 Huntington Avenue, Boston, Massachusetts 02115, USA.

The estimates used to value mortality risk reductions are a major determinant of the benefits of many public health and environmental policies. These estimates (typically expressed as the value per statistical life, VSL) describe the willingness of those affected by a policy to exchange their own income for the risk reductions they experience. While these values are relatively well studied in high-income countries, less is known about the values held by lower-income populations. We identify 26 studies conducted in the 172 countries considered low- or middle-income in any of the past 20 years; several have significant limitations. Thus there are few or no direct estimates of VSL for most such countries. Instead, analysts typically extrapolate values from wealthier countries, adjusting only for income differences. This extrapolation requires selecting a base value and an income elasticity that summarizes the rate at which VSL changes with income. Because any such approach depends on assumptions of uncertain validity, we recommend that analysts conduct a standardized sensitivity analysis to assess the extent to which their conclusions change depending on these estimates. In the longer term, more research on the value of mortality risk reductions in low- and middle-income countries is essential.
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http://dx.doi.org/10.1017/bca.2018.26DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7473065PMC
January 2019

Trading Bankruptcy for Health: A Discrete-Choice Experiment.

Value Health 2018 01 1;21(1):95-104. Epub 2017 Sep 1.

Department of Medicine, Stanford Medical School, Stanford, CA, USA.

Background: Although nearly two-third of bankruptcy in the United States is medical in origin, a common assumption is that individuals facing a potentially lethal disease opt for cure at any cost. This assumption has never been tested, and knowledge of how the American population values a trade-off between cure and bankruptcy is unknown.

Objectives: To determine the relative importance among the general American population of improved health versus improved financial risk protection, and to determine the impact of demographics on these preferences.

Methods: A discrete-choice experiment was performed with 2359 members of the US population. Respondents were asked to value treatments with varying chances of cure and bankruptcy in the presence of a lethal disease. Latent class analysis with concomitant variables was performed, weighted for national representativeness. Sensitivity analyses were undertaken to test the robustness of the results.

Results: It was found that 31.3% of the American population values cure at all costs. Nevertheless, for 8.5% of the US population, financial solvency dominates concerns for health in medical decision making. Individuals who value cure at all costs are more likely to have had experience with serious disease and to be women. No demographic characteristics significantly predicted individuals who value solvency over cure.

Conclusions: Although the average American values cure more than financial solvency, a cure-at-all-costs rubric describes the preferences of a minority of the population, and 1 in 12 value financial protection over any chances of cure. This study provides empirical evidence for how the US population values a trade-off between avoiding adverse health outcomes and facing bankruptcy. These findings bring to the fore the decision making that individuals face in balancing the acute financial burden of health care access.
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http://dx.doi.org/10.1016/j.jval.2017.07.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6739632PMC
January 2018

Dinner with Bayes: On the revision of risk beliefs.

J Risk Uncertain 2018 22;57(3):253-280. Epub 2018 Dec 22.

2Center for Risk Analysis, Harvard University, Boston, MA USA.

We study how people form and revise health risk beliefs based on food safety information. In an online experiment, subjects stated their perceived risk of contracting a foodborne illness before and after receiving information about the population average risk and the eating habits of the average consumer. Precautionary effort in handling and preparing food reduced prior risk beliefs, but did not affect the belief revision process. About one quarter of subjects either fully ignored the information provided or revised their beliefs inconsistently with the Bayesian learning hypothesis. We find several factors related to the subjects' numerical skills that explain information refusal and inconsistent belief revisions and discuss them in the context of health risks.
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http://dx.doi.org/10.1007/s11166-018-9294-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6383979PMC
December 2018

Economics in "Global Health 2035": a sensitivity analysis of the value of a life year estimates.

J Glob Health 2017 Jun;7(1):010401

Center for Health Decision Science, Harvard T.H. Chan School of Public Health, Boston, MA, USA.

Background: In "Global health 2035: a world converging within a generation," Commission on Investing in Health (CIH) adds the value of increased life expectancy to the value of growth in gross domestic product (GDP) when assessing national well-being. To value changes in life expectancy, the CIH relies on several strong assumptions to bridge gaps in the empirical research. It finds that the value of a life year (VLY) averages 2.3 times GDP per capita for low- and middle-income countries (LMICs) assuming the changes in life expectancy they experienced from 2000 to 2011 are permanent.

Methods: The CIH VLY estimate is based on a specific shift in population life expectancy and includes a 50 percent reduction for children ages 0 through 4. We investigate the sensitivity of this estimate to the underlying assumptions, including the effects of income, age, and life expectancy, and the sequencing of the calculations.

Findings: We find that reasonable alternative assumptions regarding the effects of income, age, and life expectancy may reduce the VLY estimates to 0.2 to 2.1 times GDP per capita for LMICs. Removing the reduction for young children increases the VLY, while reversing the sequencing of the calculations reduces the VLY.

Conclusion: Because the VLY is sensitive to the underlying assumptions, analysts interested in applying this approach elsewhere must tailor the estimates to the impacts of the intervention and the characteristics of the affected population. Analysts should test the sensitivity of their conclusions to reasonable alternative assumptions. More work is needed to investigate options for improving the approach.
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http://dx.doi.org/10.7189/jogh.07.010401DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5370212PMC
June 2017

The value of disease prevention vs treatment.

J Health Econ 2016 12 29;50:247-255. Epub 2016 Aug 29.

Harvard University (Center for Risk Analysis), USA; Toulouse School of Economics, France.

We present an integrated valuation model for diseases that are life-threatening. The model extends the standard one-period value-per-statistical-life model to three health prospects: healthy, ill, and dead. We derive willingness-to-pay values for prevention efforts that reduce a disease's incidence rate as well as for treatments that lower the corresponding health deterioration and mortality rates. We find that the demand value of prevention always exceeds that of treatment. People often overweight small risks and underweight large ones. We use the rank dependent utility framework to explore how the demand for prevention and treatment alters when people evaluate probabilities in a non-linear manner. For incidence and mortality rates associated with common types of cancers, the inverse-S shaped probability weighting found in experimental studies leads to a significant increase in the demand values of both treatment and prevention.
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http://dx.doi.org/10.1016/j.jhealeco.2016.08.005DOI Listing
December 2016

Understanding and improving the one and three times GDP per capita cost-effectiveness thresholds.

Health Policy Plan 2017 Feb 24;32(1):141-145. Epub 2016 Jul 24.

Center for Health Decision Science, Harvard T.H. Chan School of Public Health, Boston, MA, USA.

Researchers and policymakers have long been interested in developing simple decision rules to aid in determining whether an intervention is, or is not, cost-effective. In global health, interventions that impose costs per disability-adjusted life year averted less than three and one times gross domestic product per capita are often considered cost-effective and very cost-effective, respectively. This article explores the conceptual foundation and derivation of these thresholds. Its goal is to promote understanding of how these thresholds were derived and their implications, as well as to suggest options for improvement. These thresholds are intended to reflect the monetary value of the benefits to affected individuals, based on their preferences for spending on health vs spending on other goods and services. However, the current values were not rigorously derived, which means that their application may lead to inappropriate conclusions regarding which interventions should be adopted as well as misallocation of resources across health and other investments. Improving the basis for these cost-effectiveness thresholds is of particular importance in low- and middle-income countries, given the limited resources available and the significant needs of their populations.
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http://dx.doi.org/10.1093/heapol/czw096DOI Listing
February 2017

The Impact of Farmers' Strategic Behavior on the Spread of Animal Infectious Diseases.

PLoS One 2016 14;11(6):e0157450. Epub 2016 Jun 14.

IHAP, Université de Toulouse, INRA, ENVT, Toulouse, France.

One of the main strategies to control the spread of infectious animal diseases is the implementation of movement restrictions. This paper shows a loss in efficiency of the movement restriction policy (MRP) when behavioral responses of farmers are taken into account. Incorporating the strategic behavior of farmers in an epidemiologic model reveals that the MRP can trigger premature animal sales by farms at high risk of becoming infected that significantly reduce the efficacy of the policy. The results are validated in a parameterized network via Monte Carlo simulations and measures to mitigate the loss of efficiency of the MRP are discussed. Financial aid to farmers can be justified by public health concerns, not only for equity. This paper contributes to developing an interdisciplinary analytical framework regarding the expansion of infectious diseases combining economic and epidemiologic dimensions.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0157450PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4907430PMC
July 2017

Benefits of Regulating Hazardous Air Pollutants from Coal and Oil-Fired Utilities in the United States.

Environ Sci Technol 2016 Mar 5;50(5):2117-20. Epub 2016 Feb 5.

Emmett Environmental Law & Policy Clinic, Harvard Law School, Harvard University , Cambridge, Massachusetts 02138, United States.

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http://dx.doi.org/10.1021/acs.est.6b00239DOI Listing
March 2016

Introduction to the Special Series on Risk, Perception, and Response.

Risk Anal 2015 Oct;35(10):1766-9

Harvard University (Center for Risk Analysis), Boston, MA, USA.

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http://dx.doi.org/10.1111/risa.12520DOI Listing
October 2015

Valuing Reductions in Fatal Illness Risks: Implications of Recent Research.

Health Econ 2016 08 30;25(8):1039-52. Epub 2015 Jun 30.

Harvard University (Center for Risk Analysis), Boston, MA, USA.

The value of mortality risk reductions, conventionally expressed as the value per statistical life, is an important determinant of the net benefits of many government policies. US regulators currently rely primarily on studies of fatal injuries, raising questions about whether different values might be appropriate for risks associated with fatal illnesses. Our review suggests that, despite the substantial expansion of the research base in recent years, few US studies of illness-related risks meet criteria for quality, and those that do yield similar values to studies of injury-related risks. Given this result, combining the findings of these few studies with the findings of the more robust literature on injury-related risks appears to provide a reasonable range of estimates for application in regulatory analysis. Our review yields estimates ranging from about $4.2 million to $13.7 million with a mid-point of $9.0 million (2013 dollars). Although the studies we identify differ from those that underlie the values currently used by Federal agencies, the resulting estimates are remarkably similar, suggesting that there is substantial consensus emerging on the values applicable to the general US population. Copyright © 2015 John Wiley & Sons, Ltd.
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http://dx.doi.org/10.1002/hec.3214DOI Listing
August 2016

Introduction to the Special Series on Research Synthesis: A Cross-Disciplinary Approach.

Risk Anal 2015 Jun 17;35(6):963-70. Epub 2015 Jun 17.

Harvard University (Center for Risk Analysis), 677 Huntington Ave, Boston, MA, USA.

To estimate the effects of a policy change, analysts must often rely on available data as time and resource constraints limit their ability to commission new primary research. Research synthesis methods-including systematic review, meta-analysis, and expert elicitation-play an important role in ensuring that this evidence is appropriately weighed and considered. We present the conclusions of a multidisciplinary Harvard Center for Risk Analysis project that evaluated and applied these methods, and introduce the resulting series of articles. The first step in any analysis is to clearly define the problem to be addressed; the second is a systematic review of the literature. Whether additional analysis is needed depends on the quality and relevance of the available data to the policy question, and the likely effect of uncertainty on the policy decision. Meta-analysis promotes understanding the variation between studies and may be used to combine the estimates to develop values for application in policy analysis. Formal, structured expert elicitation promotes careful consideration of the evidence when data are limited or inconsistent, and aids in extrapolating to the policy context. Regardless of the methods used, clear communication of the approach, assumptions, and uncertainty is essential.
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http://dx.doi.org/10.1111/risa.12437DOI Listing
June 2015

Research Synthesis and the Value per Statistical Life.

Risk Anal 2015 Jun 7;35(6):1086-100. Epub 2015 Apr 7.

Harvard University, Boston, MA, USA.

The value of small changes in mortality risk, conventionally expressed as the value per statistical life (VSL), is a major determinant of the benefits of many environmental, health, and safety regulations and other policies. However, selecting an appropriate value is challenging. Different studies yield different results and analysts often find they lack estimates that are directly applicable to the policy they are assessing. Research-synthesis methods are widely used to address these concerns in many fields, yet we find only limited applications to estimating VSL. More structured, criteria-driven review of the available studies is an important first step. Additional meta-analyses that use such review as a starting point are needed to explore variation across studies as well as to adjust estimates to better fit different policy contexts. Carefully designed expert elicitation is significantly underutilized and is particularly important when the available research is limited or inconsistent. Although greater use of such methods is likely to enhance the credibility of the VSL estimates applied in policy analyses, as well as provide greater insights into the advantages and limitations of the available research, it is not clear how much the resulting estimates will vary from those currently used. In the United States, these estimates are generally around $9 million.
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http://dx.doi.org/10.1111/risa.12366DOI Listing
June 2015

Cost assessment of the movement restriction policy in France during the 2006 bluetongue virus episode (BTV-8).

Prev Vet Med 2014 Dec 28;117(3-4):577-89. Epub 2014 Oct 28.

Université de Toulouse, Institut National Polytechnique (INP), Ecole Nationale Vétérinaire de Toulouse (ENVT), UMR1225, Interaction Hôte Agent Pathogène (IHAP), 31076 Toulouse, France; INRA, US0685, Observatoire du Développement Durable (ODR), 31326 Auzeville, France; INRA, UMR1225, IHAP, 31076 Toulouse, France.

This study aims at evaluating the costs of the movement restriction policy (MRP) during the 2006 BTV-8 epidemic in France for the producers of 6-9 month old Charolais beef weaned calves (BWC), an important sector that was severely affected by the restrictions imposed. This study estimates the change in the number of BWC sold that was due to the movement restrictions, and evaluates the economic effect of the MRP. The change in BWC sold by producers located inside the restriction zone (RZ) was analyzed for 2006 by using a multivariate matching approach to control for any internal validity threat. The economic evaluation of the MRP was based on several scenarios that describe farms' capacity constraints, feeding prices, and the animal's selling price. Results show that the average farmer experienced a 21% decrease in animals sold due to the MRP. The economic evaluation of the MRP shows a potential gain during the movement standstill period in the case of no capacity constraint faced by the farm and food self-sufficiency. This gain remains limited and close to zero in case of a low selling price and when animals are held until they no longer fit the BWC market so that they cannot be sold as an intermediate product. Capacity constraints represent a tremendous challenge to farmers facing movement restrictions and the fattening profit becomes negative under such conditions. The timing and length of the movement standstill period significantly affect the profitability of the strategy employed by the farmer: for a 5.5 month-long standstill period with 3.5 months of cold weather, farmers with capacity constraints have stronger incentives to leave their animals outside during the whole period and face higher mortality and morbidity rates than paying for a boarding facility for the cold months. This is not necessarily true for a shorter standstill period. Strategies are also sensitive to the feed costs and to the food self-sufficiency of the farm. Altogether, the present work shows the farmer's vulnerability to animal movement restrictions and quantifies the costs of the standstill. These results should assist decision-makers who seek to calculate adequate subsidies/aid or to efficiently allocate resources to prevent future outbreaks.
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http://dx.doi.org/10.1016/j.prevetmed.2014.10.010DOI Listing
December 2014

The welfare value of FDA's mercury-in-fish advisory: a dynamic reanalysis.

J Health Econ 2014 Sep 19;37:113-22. Epub 2014 Jun 19.

Harvard University (Center for Risk Analysis), United States; Toulouse School of Economics (LERNA-INRA), France.

Assessing the welfare impact of consumer health advisories is a thorny task. Recently, Shimshack and Ward (2010) studied how U.S. households responded to FDA's 2001 mercury-in-fish advisory. They found that the average at-risk household reduced fish consumption by 21%, resulting in a 17%-reduction in mercury exposure at the cost of a 21%-reduction in cardioprotective omega-3 fatty acids. Based on a static assessment of the health costs and benefits Shimshack and Ward concluded that the advisory policy resulted in an overall consumer welfare loss. In this note, we propose a dynamic assessment that links the long-term cardiovascular health effects of the advisory to life-cycle consumption. We find that under reasonable assumptions the welfare loss might be much larger than suggested. Our analysis highlights the importance of accounting for dynamic effects when evaluating persistent changes in exposure to environmental health risks.
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http://dx.doi.org/10.1016/j.jhealeco.2014.06.005DOI Listing
September 2014

The social value of mortality risk reduction: VSL versus the social welfare function approach.

J Health Econ 2014 May 18;35:82-93. Epub 2014 Feb 18.

Toulouse School of Economics (LERNA-INRA), 21 allée de Brienne, 31000 Toulouse, France.

We examine how different welfarist frameworks evaluate the social value of mortality risk reduction. These frameworks include classical, distributively unweighted cost-benefit analysis--i.e., the "value per statistical life" (VSL) approach-and various social welfare functions (SWFs). The SWFs are either utilitarian or prioritarian, applied to policy choice under risk in either an "ex post" or "ex ante" manner. We examine the conditions on individual utility and on the SWF under which these frameworks display sensitivity to wealth and to baseline risk. Moreover, we discuss whether these frameworks satisfy related properties that have received some attention in the literature, namely equal value of risk reduction, preference for risk equity, and catastrophe aversion. We show that the particular manner in which VSL ranks risk-reduction measures is not necessarily shared by other welfarist frameworks.
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http://dx.doi.org/10.1016/j.jhealeco.2014.02.001DOI Listing
May 2014

Effect of the Fukushima nuclear accident on the risk perception of residents near a nuclear power plant in China.

Proc Natl Acad Sci U S A 2013 Dec 18;110(49):19742-7. Epub 2013 Nov 18.

State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, People's Republic of China.

We assessed the influence of the Fukushima nuclear accident (FNA) on the Chinese public's attitude and acceptance of nuclear power plants in China. Two surveys (before and after the FNA) were administered to separate subsamples of residents near the Tianwan nuclear power plant in Lianyungang, China. A structural equation model was constructed to describe the public acceptance of nuclear power and four risk perception factors: knowledge, perceived risk, benefit, and trust. Regression analysis was conducted to estimate the relationship between acceptance of nuclear power and the risk perception factors while controlling for demographic variables. Meanwhile, we assessed the median public acceptable frequencies for three levels of nuclear events. The FNA had a significant impact on risk perception of the Chinese public, especially on the factor of perceived risk, which increased from limited risk to great risk. Public acceptance of nuclear power decreased significantly after the FNA. The most sensitive groups include females, those not in public service, those with lower income, and those living close to the Tianwan nuclear power plant. Fifty percent of the survey respondents considered it acceptable to have a nuclear anomaly no more than once in 50 y. For nuclear incidents and serious incidents, the frequencies are once in 100 y and 150 y, respectively. The change in risk perception and acceptance may be attributed to the FNA. Decreased acceptance of nuclear power after the FNA among the Chinese public creates additional obstacles to further development of nuclear power in China and require effective communication strategies.
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http://dx.doi.org/10.1073/pnas.1313825110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3856800PMC
December 2013

National HIV prevalence estimates for sub-Saharan Africa: controlling selection bias with Heckman-type selection models.

Sex Transm Infect 2012 Dec;88 Suppl 2:i17-23

Harvard School of Public Health, Department of Global Health and Population, 665 Huntington Ave, Building 1, Boston, MA 02115, USA.

Objectives: Population-based HIV testing surveys have become central to deriving estimates of national HIV prevalence in sub-Saharan Africa. However, limited participation in these surveys can lead to selection bias. We control for selection bias in national HIV prevalence estimates using a novel approach, which unlike conventional imputation can account for selection on unobserved factors.

Methods: For 12 Demographic and Health Surveys conducted from 2001 to 2009 (N=138 300), we predict HIV status among those missing a valid HIV test with Heckman-type selection models, which allow for correlation between infection status and participation in survey HIV testing. We compare these estimates with conventional ones and introduce a simulation procedure that incorporates regression model parameter uncertainty into confidence intervals.

Results: Selection model point estimates of national HIV prevalence were greater than unadjusted estimates for 10 of 12 surveys for men and 11 of 12 surveys for women, and were also greater than the majority of estimates obtained from conventional imputation, with significantly higher HIV prevalence estimates for men in Cote d'Ivoire 2005, Mali 2006 and Zambia 2007. Accounting for selective non-participation yielded 95% confidence intervals around HIV prevalence estimates that are wider than those obtained with conventional imputation by an average factor of 4.5.

Conclusions: Our analysis indicates that national HIV prevalence estimates for many countries in sub-Saharan African are more uncertain than previously thought, and may be underestimated in several cases, underscoring the need for increasing participation in HIV surveys. Heckman-type selection models should be included in the set of tools used for routine estimation of HIV prevalence.
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http://dx.doi.org/10.1136/sextrans-2012-050636DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3512441PMC
December 2012

Risk trade-offs in fish consumption: a public health perspective.

Environ Sci Technol 2012 Nov 8;46(22):12337-46. Epub 2012 Nov 8.

LERNA-INRA, Toulouse School of Economics, 1 Rue des Amidonniers, 31000 Toulouse, France.

Fish consumption advisories instruct vulnerable consumers to avoid high mercury fish and to limit total fish intake to reduce neurotoxic risk. Consumption data from the U.S. suggest that nontarget consumers also respond to such advice. These consumers reduce exposure to mercury and other toxicants at the cost of reduction in cardioprotective fatty acids. We present a probabilistic model to assess these risk trade-offs. We use NHANES consumption data to simulate exposure to contaminants and nutrients in fish, employ dose-response relationships to convert exposure to health end points, and monetize them using benefit transfer. Our results suggest that newborns gained on average 0.033 IQ points from their mothers' compliance with the prominent FDA/EPA advisory. The welfare gain for a birth cohort is estimated at $386 million. This gain could be fully offset by increments in cardiovascular risk if 0.6% of consumers aged 40 and older reduced fish intake by one monthly meal until they reached the age of 60 or if 0.1% of them permanently reduced fish intake.
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http://dx.doi.org/10.1021/es302652mDOI Listing
November 2012
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