Annual Review of Public Health - Volume 22, 2001

The occurrence of U-shaped dose-response relationships (often termed hormesis) has been documented in numerous biological, toxicological, and pharmacological investigations. Many of the endpoints studied are of considerable significance to public health (e.g. body weight, cholesterol levels, ethanol consumption, longevity, cancer incidence, etc). Despite the fact that U-shaped dose-responses are widely and independently observed, little attempt has been made to assess this phenomenon in an integrative manner. This review provides an overview of the historical foundations of hormesis and a discussion of its definition within a mechanistic framework. The occurrence, generalizability, and biological significance of U-shaped dose-response relationships along with the concept of biological optimality are addressed.

The cost of providing graduate medical education to the approximately 100,000 medical residents in the United States is approximately $18 billion. The government, primarily through the Medicare program, funds almost two thirds of the cost. Unfortunately, the federal government lacks a coherent policy with respect to what objectives it wants to achieve for this expenditure. This article traces (a) the evolution of graduate medical education funding; (b) current proposals to reform the funding mechanism; (c) how the Medicare program currently funds graduate medical education; (d) how funds are allocated to specific institutions; and (e) specific policy objectives that academic medical centers should be held accountable for achieving in return for receiving public funds.

The lack of an outpatient prescription drug benefit under Medicare has become a conspicuous omission in the face of accelerated growth in prescription drug expenditures and increased availability of highly effective medications. This article provides a critical review of the empirical evidence on the effect of drug coverage on the use of prescription drugs, health care outcomes, and health care costs among Medicare beneficiaries. The existing literature provides considerable evidence that drug coverage is associated with greater use of all drugs and clinically essential medications and that not all forms of coverage provide the same protection. Longitudinal evidence from elderly and disabled persons in Medicaid indicates that restricting coverage has serious adverse health outcomes for sick and low-income beneficiaries that actually lead to increased health care costs.

Protecting workers and the public from toxic chemicals, particularly carcinogens, has been a principal goal of public policy. In the absence of knowing by what mechanism of action a toxicant harms people, regulatory toxicology assumes that even tiny doses can cause harm. Risk aversion has led to legislation and regulation that seek to ban toxic chemicals or lower exposure to trivial levels. Contradicting this policy, many studies show health benefits from low-level exposure to toxicants, including some carcinogens. This is known as hormesis. Thus, hormesis could lead to a fundamental change in the policy for regulating toxic substances. In particular, all toxicants that benefit health at low-level exposures should face similar change in regulations for low-dose exposure. The result would be the dissolving of the source of differences in policy for carcinogens and noncarcinogens at low doses. Two questions must be answered before hormesis can be incorporated into regulatory policy. (a) Are there sensitive individuals who would be harmed at doses that would help most people? (b) Is the hormetic effect toxicant specific or would exposure to just a few toxicants achieve the full benefit from hormesis?

The public release of health care–quality data into more formalized consumer health report cards is intended to educate consumers, improve quality of care, and increase competition in the marketplace The purpose of this review is to evaluate the evidence on the impact of consumer report cards on the behavior of consumers, providers, and purchasers. Studies were selected by conducting database searches in Medline and Healthstar to identify papers published since 1995 in peer-review journals pertaining to consumer report cards on health care. The evidence indicates that consumer report cards do not make a difference in decision making, improvement of quality, or competition. The research to date suggests that perhaps we need to rethink the entire endeavor of consumer report cards. Consumers desire information that is provider specific and may be more likely to use information on rates of errors and adverse outcomes. Purchasers may be in a better position to understand and use information about health plan quality to select high-quality plans to offer consumers and to design premium contributions to steer consumers, through price, to the highest-quality plans.

Cancer is a major public health issue and represents a significant burden of disease. In this chapter, we analyze the main measures of burden of disease as relate to cancer. Specifically, we review incidence and mortality, years of life lost from cancer, and cancer prevalence. We also discuss the economic burden of cancer, including cost of illness, phase-specific and long-term costs, and indirect costs. We then examine the impact of cancer on health-related quality of life as measured in global terms (disability-adjusted life years and quality-adjusted life years) and using evaluation-oriented applications of health-related quality of life scales. Throughout, we note the relative strengths and weaknesses of the various approaches to measuring the burden of cancer as well as the methodologic challenges that persist in burden-of-illness research. We conclude with a discussion of the research agenda to improve our understanding of the burden of cancer and of illness more generally.

Investigators often gather repeated measures on study subjects to directly measure how a subject's response changes with changes in explanatory variables. This paper focuses on several statistical issues related to assessing change with longitudinal and clustered binary data. Many popular approaches for analyzing repeated binary outcomes measure cross-sectional or between-subject, rather than within-subject, effects of covariates. The class of models known as cluster specific measures within-subject effects of covariates on responses but are subject to additional statistical complications. It is useful to decompose covariates into between- and within-cluster components. This paper describes several approaches that yield consistent estimates of the within-subject covariate effects of interest. Example data from three studies illustrate the results.

In response to rising demands for timely economic data on new medical technologies, cost-effectiveness studies are increasingly being conducted alongside clinical trials. Because of the historical differences in perspective and methods between cost-effectiveness studies and clinical trials, the design phase of these hybrid trials requires special consideration. Cost-effectiveness studies require more comprehensive evaluations of outcomes than the endpoints typically measured in clinical trials. Often, these comprehensive outcome measures (such as quality of life) prove useful for interpreting the other endpoints measured in the trial, as well as for estimating the cost-effectiveness of the intervention. In this manuscript, we discuss several aspects related to the design of joint clinical/economic trials, including study perspective, hypothesis testing, sample size estimation, and methods for collecting cost and outcome data. We also discuss issues that may limit the external validity of the cost-effectiveness results of these trials. Many potential threats to external validity can be successfully addressed if they are identified and accounted for in the design phase of the study.

The term social ecology refers to the nested arrangement of family, school, neighborhood, and community contexts in which children grow up. In this chapter, new directions in public health science as reflected in the theoretical and methodological implications of the concept are explored. The contributions of this ecologically oriented approach to child health practice, designed as it is from a health promotions perspective, are considered. A critique of the term social capital is also presented because of its growing popularity in matters of child health. The point is made that application of this vague term carries the serious risk of misspecifying social phenomena. Future trends in the promotion of child well-being are in a position to flourish given the confluence of advances in theory, methods, and analytical capacity. The capacity to benefit children is also enhanced as public health science aims to translate the principles of child rights into health practice and policy.

Group randomized trials (GRTs) in public health research typically use a small number of randomized groups with a relatively large number of participants per group. Two fundamental features characterize GRTs: a positive correlation of outcomes within a group, and the small number of groups. Appropriate consideration of these fundamental features is essential for design and analysis. This paper presents the fundamental features of GRTs and the importance of considering these features in design and analysis. It also reviews and contrasts the main analytic methods proposed for GRTs, emphasizing the assumptions required to make these methods valid and efficient. Also discussed are various design issues, along with guidelines for choosing among them. A real data example illustrates these issues and methods.

Consideration of confounding is fundamental to the design, analysis, and interpretation of studies intended to estimate causal effects. Unfortunately, the word confounding has been used synonymously with several other terms, and it has been used to refer to at least four distinct concepts. This paper provides an overview of confounding and related concepts based on a counterfactual model of causation. In this context, which predominates in nonexperimental research, confounding is a source of bias in the estimation of causal effects. Special attention is given to the history of definitions of confounding, the distinction between confounding and confounders, problems in the control of confounding, the relations of confounding to exchangeability and collapsibility, and confounding in randomized trials.

Electronically available administrative data are increasingly used by public health researchers and planners. The validity of the data source has been established, and its strengths and weaknesses relative to data abstracted from medical records and obtained via survey are documented. Administrative data are available from a variety of state, federal, and private sources and can, in many cases, be combined. As a tool for planning and surveillance, administrative data show great promise: They contain consistent elements, are available in a timely manner, and provide information about large numbers of individuals. Because they are available in an electronic format, they are relatively inexpensive to obtain and use. In the United States, however, there is no administrative data set covering the entire population. Although Medicare provides health care for an estimated 96% of the elderly, age 65 years and older, there is no comparable source for those under 65.

Rapid, small surveys are routinely done in much of the developing world but are less common in the United States. We present as an example a rapid survey of immunization status and other factors in a predominantly Hispanic region in Los Angeles. The survey united county employees, students, and community volunteers, first to enumerate the eligible population and then to conduct in-person interviews. Sampling was done in two stages in a downtown region of Los Angeles. Over the course of two weekends and during clean-up the following week, volunteers and others enumerated 718 eligible children in 30 clusters (i.e. groups of blocks). At the second stage, also in two weekends with midweek clean-up, we selected by simple random sample 10 children per cluster. The parents or legal guardians of 270 children were interviewed about vaccination issues, including home presence of an immunization card. Nearly one fourth of the respondents did not have a home telephone number and thus would have been underrepresented in a telephone survey. Information from such rapid surveys is important for local program planning and evaluation.

Illicit drug use is an important public health problem with broad social costs. The low effectiveness of prevention efforts leaves treatment of drug dependence as one of the most powerful means of fighting illicit drug use. Treatment reduces drug use and crime and increases individuals' functioning. However, programs that treat drug dependence have high dropout rates and low completion rates. In addition, some individuals continue to use drugs while in treatment, and relapse is common. Furthermore, only a fraction of those who need treatment receive it. Recently, there have been important innovations that reduce barriers and increase effectiveness of treatment. These innovations include new pharmacological agents, novel counseling strategies, promising ways to motivate, and treatment in new settings. This paper describes standard treatments and recent innovations designed to increase (a) effectiveness of treatment, (b) motivation to seek care, (c) access, (d) retention, and (e) cost-effectiveness. We provide criteria on how these innovations should be evaluated in order to determine which should be adopted, funded, and transferred to existing and future treatment programs.

This article summarizes recent developments in the United Kingdom, the Netherlands, Switzerland, and the new Baltic states that reflect the influence of US managed care concepts and practices. We emphasize (a) developments in restructuring traditional health insurance mechanisms by shifting premium and out-of-pocket burdens to consumers so as to constrain demand and costs and (b) reliance on prospective hospital budgets and case management by primary physicians. Social insurance mechanisms and universal coverage remain national tasks as well as basic components of the social structure of most European countries. Full open-market competition between traditional sick funds and private insurance companies and the introduction of for-profit MCOs beholden to their shareholders appears unlikely on other than an experimental basis. Increased competition between providers may well result from the new right of insurers and payers to contract with medical care providers of their choice. It remains to be shown how far these experiments, which differ substantially between the countries examined, will succeed in their objectives and become permanent features of their national systems.

The high and still increasing prevalence of obesity in US children, adolescents, and adults poses a major economic and health threat to our society. The three reviews in this minisymposium on obesity explore the health issues by: 1) describing the public health impact of obesity; 2) examining the multiple and complex environmental influences on eating and physical activity patterns; and 3) considering how the development of obesity during childhood and adolescence can be prevented through interventions in school, family, and primary care settings. This overview explains the importance, for effective long-term obesity prevention and control, of intersectoral policy and environmental initiatives—in addition to behavior change approaches aimed at individuals. The need for public health professionals to influence and operate within a variety of non-health sectors such as transportation, education, urban planning, and commerce may be seen as the greatest barrier but may also be the greatest opportunity.

Obesity has increased dramatically over the past two decades and currently about 50% of US adults and 25% of US children are overweight. The current epidemic of obesity is caused largely by an environment that promotes excessive food intake and discourages physical activity. This chapter reviews what is known about environmental influences on physical activity and eating behaviors. Recent trends in food supply, eating out, physical activity, and inactivity are reviewed, as are the effects of advertising, promotion, and pricing on eating and physical activity. Public health interventions, opportunities, and potential strategies to combat the obesity epidemic by promoting an environment that supports healthy eating and physical activity are discussed.

In this review, we address the natural history of obesity in children, the most promising family- and school-based approaches to the prevention of obesity, and the barriers and opportunities associated with secondary prevention. In childhood, the most important periods of risk appear to be the periods of adiposity rebound and adolescence. Caution regarding the period of adiposity rebound is still warranted, because it is not yet clear that early rebound is attributable to changes in body fat. Families and schools represent the most important foci for preventive efforts in children and adolescents. One productive approach is to proceed from an examination of factors that affect energy balance to the identification of more proximal influences on those factors. This approach may help to narrow the strategies necessary to prevent or treat childhood obesity. For example, television viewing affects both energy intake and energy expenditure, and therefore represents a logical target for interventions. Anticipatory guidance by pediatricians may offer an effective mechanism by which to change parental attitudes and practices regarding television viewing. A similar process is used to emphasize the potential influence of school-based interventions directed at changes in food choices and sedentary behavior.