Health Policy and Management
Harvard School of Public Health
James K. Hammitt, Ph.D., is Professor of Economics and Decision Sciences in the Departments of Health Policy and Management and of Environmental Health and Director of the Harvard Center for Risk Analysis. Professor Hammitt's research focuses on the development and application of quantitative methods - including benefit-cost, decision, and risk analysis - to health and environmental policy. Topics of interest include management of long-term environmental issues with major scientific uncertainties, such as global climate change and stratospheric-ozone depletion, evaluation of ancillary benefits and countervailing risks associated with risk-control measures, and characterization of social preferences over health and environmental risks using revealed-preference, contingent-valuation, and health-utility methods. Dr. Hammitt earned his A.B. and Sc.M. in Applied Mathematics in 1978, his M.P.P., in 1981, and his Ph.D. in Public Policy in 1988, all from Harvard University. He has been appointed Senior Mathematician at the RAND Corporation (Santa Monica, California) and to the Pierre-de-Fermat Chaire d’Éxcellence at the Université de Toulouse (France).
We developed a probabilistic model to characterize the plausible distribution of health and economic benefits that would accrue to the U.S. population following reduction of methyl mercury (MeHg) exposure. MeHg, a known human developmental neurotoxicant, may increase fatal heart attack risks. Model parameters reflect current understanding of the relationships between MeHg intake, health risks, and societal valuation of these risks. The expected monetary value of the annual health benefits generated by a 10% reduction in U.S. population exposure to MeHg for one year is $860 million; 80% of this is associated with reductions in fatal heart attacks and the remainder with IQ gains. The plausible distribution of the benefits is quite broad with 5th and 95th percentile estimates of approximately $50 million and $3.5 billion, respectively. The largest source of uncertainty is whether epidemiological associations between MeHg exposure and fatal heart attacks reflect causality. The next largest sources of uncertainty concern the slope of the relationship between maternal MeHg exposure and reduced intelligence among children and whether this relationship exhibits a threshold. Our analysis suggests that the possible causal relationship between MeHg exposure and fatal heart attacks should be better characterized, using additional epidemiological studies and formally elicited expert judgment.
We developed a probabilistic model to characterize the plausible distribution of health and economic benefits that would accrue to the U.S. population following reduction of methyl mercury (MeHg) exposure. MeHg, a known human developmental neur... (more »)
OBJECTIVE: UNAIDS and country analysts use a simple infectious disease model, embedded in the Estimation and Projection Package (EPP), to generate annual updates on the global HIV/AIDS epidemic. Our objective was to develop modifications to the current model that improve fit to recently observed prevalence trends across countries.
METHODS: Our proposed alternative to the current EPP approach simplifies the model structure and explicitly models changes in average infection risk over time, operationalised using penalised B-splines in a Bayesian framework. We also present an alternative approach to initiating the epidemic that improves standardisation and efficiency, and add an informative prior distribution for changes in infection risk beyond the last data point that enhances the plausibility of short-term extrapolations.
RESULTS: The spline-based model produces better fits than the current model to observed prevalence trends in settings that have recently experienced levelling or rising prevalence following a steep decline, such as Uganda and urban Rwanda. The model also predicts a deceleration of the decline in prevalence for countries with recent experience of steady declines, such as Kenya and Zimbabwe. Estimates and projections from our alternative model are comparable to those from the current model where the latter performs well.
CONCLUSIONS: A more flexible epidemiological model that accommodates changing infection risk over time can provide better estimates and short-term projections of HIV/AIDS incidence, prevalence and mortality than the current EPP model. The alternative model specification can be incorporated easily into existing analytical tools that are used to produce updates on the global HIV/AIDS epidemic.
OBJECTIVE: UNAIDS and country analysts use a simple infectious disease model, embedded in the Estimation and Projection Package (EPP), to generate annual updates on the global HIV/AIDS epidemic. Our objective was to develop m... (more »)
We assessed how much, if anything, people would pay for a laboratory test that predicted their future disease status. A questionnaire was administered via an internet-based survey to a random sample of adult US respondents. Each respondent answered questions about two different scenarios, each of which specified: one of four randomly selected diseases (Alzheimer's, arthritis, breast cancer, or prostate cancer); an ex ante risk of developing the disease (randomly designated 10 or 25%); and test accuracy (randomly designated perfect or 'not perfectly accurate'). Willingness-to-pay (WTP) was elicited with a double-bounded, dichotomous-choice approach. Of 1463 respondents who completed the survey, most (70-88%, depending on the scenario) were inclined to take the test. Inclination to take the rest was lower for Alzheimer's and higher for prostate cancer compared with arthritis, and rose somewhat with disease prevalence and for the perfect versus imperfect test. Median WTP varied from $109 for the imperfect arthritis test to $263 for the perfect prostate cancer test. Respondents' preferences for predictive testing, even in the absence of direct treatment consequences, reflected health and non-health related factors, and suggests that conventional cost-effectiveness analyses may underestimate the value of testing
We assessed how much, if anything, people would pay for a laboratory test that predicted their future disease status. A questionnaire was administered via an internet-based survey to a random sample of adult US respondents. Each respondent answ... (more »)
Regulations designed to increase homeland security often require balancing large costs against highly uncertain benefits. An important component of these benefits is the reduced risk of fatalities from terrorist attacks. While the risk to an individual appears small, the benefits may be large when aggregated over the population. U.S. regulatory agencies have well-established approaches for valuing mortality risks, but address risks that differ in significant respects from those associated with terrorism. The best available estimates of the value of small risk reductions, expressed as the value per statistical life (VSL), average about $6.5 million. However, terrorism-related risks may be perceived as more dreaded and ambiguous, and less controllable and voluntary, than the workplace risks underlying many VSL estimates. These factors may increase the VSL appropriate for terrorism risks, possibly doubling the value.
Regulations designed to increase homeland security often require balancing large costs against highly uncertain benefits. An important component of these benefits is the reduced risk of fatalities from terrorist attacks. While the risk to an indiv... (more »)
By reducing risk of large out-of-pocket medical expenses, comprehensive social health insurance may reduce households' motivation to engage in precautionary behaviors such as saving, procurement of private insurance, and spousal labor-force participation. We use the natural experiment provided by the 1995 introduction of National Health Insurance in Taiwan to examine these effects, using pre-existing differences in access to health insurance (tied to the household headâ€™s and spouseâ€™s joint employment status) to identify the effects of increasing insurance coverage. We find that comprehensive health insurance has a statistically significant and large effect on household savings, but no significant effects on purchase of private accident insurance and spousal employment. [ABSTRACT FROM AUTHOR]; Copyright of Review of Economics of the Household is the property of Springer Science & Business Media B.V. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
By reducing risk of large out-of-pocket medical expenses, comprehensive social health insurance may reduce households' motivation to engage in precautionary behaviors such as saving, procurement of private insurance, and spousal labor-force partic... (more »)