Annual Review of Public Health - Volume 20, 1999

The history of occupational health in the United States during the twentieth century demonstrates pendular swings, with periods of rapid progress followed by periods of reversal. Happily, the last three decades have witnessed the most impressive gains, with establishment of a near-universal system for regulating conditions in the workplace, legitimization and growth of the occupational health professions, a marked increase in scientific research, most notably epidemiology, and the transfer of knowledge about occupational health to affected workers and the larger US population. Not surprisingly, rates of injury and illness have fallen.

However, analysis of these cyclical historic changes suggests that extrinsic factors—broad social currents, changes in health care financing, and societal perceptions of health and disease—have dominated over enhanced scientific knowledge, technologic changes or professional achievements, usually the determinants of medical or public health advances. Practitioners of occupational health are not, and have never been, in a particularly advantageous position to fashion future events in their own field, and the current situation, however encouraging, is likely no exception.

This paper considers ways of thinking about causes and prevention that could guide epidemiology beyond the present era. Discontent with modern epidemiology, in the face of its substantial achievements, is taken as a sign that the guiding principles of the discipline warrant reconsideration. To begin this task, current practices are placed within an historical perspective, in a review of the dominant ideas of successive eras in epidemiology. Then the premises and constraints of the present era of chronic disease epidemiology, with its risk factor paradigm, are specified. Finally, elements of a causal paradigm for an emerging era are proposed. This paradigm encourages thinking about causes at multiple levels of organization and within the historical context of both societies and individuals. The proposed approach aims to preserve and build on the contributions of past eras, as well as the present one.

Environmental health has evolved rapidly in recent decades, drawing largely on new analytic technologies, advanced data acquisition and modeling, mechanistic studies in toxicology, and the conceptual framework of risk assessment. The latter combines toxicologic and epidemiologic data with improved techniques for quantifying exposure, producing estimates of risks from environmental hazards or conditions to selected target populations. The public and governments have become increasingly concerned with environmental health and quality. The major lessons have been (a) environmental-health scientists must participate in policy debates; (b) environmental health problems are exceedingly complex and require interdisciplinary research; and (c) environmental health is a global issue. The globalization of commerce, the untested impact of international trade agreements, increased migration, and especially increased population, have profound impact on the quality as well as availability of air, water, land, and food. Global atmospheric transport of pollutants and the effect on atmosphere and climate are two examples of globalization of environmental health.

The chapter begins with a reminder that forecasting changes in the health care sector a quarter to a third of a century in the future is likely to be a losing effort, based on past experience. It next considers changing organization and financing and questions that managed care and market competition will be the key forces introducing change. The author looks forward to the passage of universal health insurance coverage for essential care by early in the new century, with patients having to pay for more choice and more quality. The analysis next focuses on the physician supply and points to three challenges: how to moderate the numbers being trained; whether to reconsider the conventional wisdom of training more generalists; and how to support more resources for the National Health Service Corps to improve coverage in underserved areas. The author predicts the restructuring of acute care hospitals, with a marked reduction of in-patient beds, and that leading-edge research-oriented academic health centers should be able to remain out in front. There are also potential gains in health status from prevention and molecular medicine in a nation where chronic disease will dominate.

A lesson of the first half of the century was that growth and technological development brought new health problems and challenges in their wake, many of which were to prove more intractable to technological fixes than the ones that had been so dramatically fixed before. Massive expansions of resources in support of the extension of these medical fixes resulted in an escalation of costs that had to be reigned in by breaking from the resource-based planning cycle that had prevailed through two eras of expansion. The 1970s ushered in an era of cost containment as the central theme of new policies. They included provisions for health promotion that sought to find new handles on the intractable social and behavioral aspects of the demand for health care resources, especially through primary prevention and building of capacity for community, family, and individual self-management of health problems and programs. Lessons from this era for public health in the next century are considered.

With an increasingly older population, there is considerable interest in understanding the potential for risk factor interventions in order to prevent, postpone, or slow down the common diseases seen in older persons. However, it is often reported that the strength of association between risk factors and common disease outcomes decreases with increasing age. Actually, many different age-related patterns are observed. Understanding these patterns requires knowledge of issues related to the pathophysiology of aging, including age-related physiologic and metabolic alterations, detection and diagnosis of disease in the elderly, measurement of risk factors, sample selection, comorbidity, competing risks, selective survival, ceiling effects, and methods of analysis in aging populations.

This article considers the rise of the randomized clinical trial during the twentieth century. Before such development could begin, probability and statistics needed to merge. Sir RA Fisher introduced randomization in the 1920s and, beginning in the 1930s and 1940s, randomized clinical trials in humans were being performed by using the statistical-hypothesis-testing paradigm. Randomization gave unbiased comparisons and a way to perform hypothesis testing without model assumptions. To preserve the benefits of randomization, a type of analysis called intent-to-treat analysis is appropriate. Needed development has occurred and is occurring in refining ethical standards, monitoring trials of serious irreversible endpoints while preserving type-I error, and instituting independent data- and safety-monitoring boards. Recent methodology has also been concerned with the appropriateness of using surrogate endpoints. A current area of debate is the appropriateness of using Bayesian statistical methods in this context.

Important questions about health care are often addressed by studying health care utilization. Utilization data have several characteristics that make them a challenge to analyze. In this paper we discuss sources of information, the statistical properties of utilization data, common analytic methods including the two-part model, and some newly available statistical methods including the generalized linear model. We also address issues of study design and new methods for dealing with censored data. Examples are presented.

The Cox proportional-hazards regression model has achieved widespread use in the analysis of time-to-event data with censoring and covariates. The covariates may change their values over time. This article discusses the use of such time-dependent covariates, which offer additional opportunities but must be used with caution. The interrelationships between the outcome and variable over time can lead to bias unless the relationships are well understood. The form of a time-dependent covariate is much more complex than in Cox models with fixed (non–time-dependent) covariates. It involves constructing a function of time. Further, the model does not have some of the properties of the fixed-covariate model; it cannot usually be used to predict the survival (time-to-event) curve over time. The estimated probability of an event over time is not related to the hazard function in the usual fashion. An appendix summarizes the mathematics of time-dependent covariates.

Can an analytical tool for comparing environmental risks and policy activities be used to evaluate their relative efficacy in ultimately changing the allocation of public funds? Some insight is possible through a review of comparative risk projects that have been carried out at the city, state, and national levels, as well as among Indian tribes, over the past 12 years. The lessons from this review should apply to the field of public health. For every comparison of environmental issues, such as clean-air standards with fish consumption advisories, there is a parallel discussion of public health priorities and strategies, such as antismoking and pregnancy prevention programs, immunization programs and disease surveillance efforts, or well-baby clinics and food safety programs. Lessons from comparative risk projects and processes may offer the public health community new ways of thinking about using stakeholder assessment processes in developing public health policy.

To search for unexplained patterns in cancer incidence, we analyzed data from 1975 to 1994 that represent ∼10% of the population of the United States. Our analysis focused on long-term time trends in incidence and on deviations from those trends attributable to birth cohorts or to calendar periods. On average, cancer incidence rose 0.8% annually in white women and 1.8% in white men. After removing several cancers related to smoking and increased screening, average annual increases fell to 0.1% in white women but persisted at 1.7% in white men. In particular, yearly increases in non-Hodgkin's lymphoma averaged 2.4% in white women and 4.7% in white men. Among men, incidence changes attributable to cohorts grew progressively larger from one cohort to the next. Cancer incidence patterns among black men and women were similar to those among whites despite smaller population sizes. Unexplained patterns of cancer incidence may signal changes in underlying risk factors and highlight the continuing need for research on cancer etiology and prevention.

Eradication is the permanent reduction to zero of the worldwide incidence of infection caused by a specific agent as a result of deliberate efforts; intervention measures are no longer needed. To date, the only infectious disease that has been eradicated is smallpox. Poliomyelitis is targeted for eradication by the year 2000, and the eradication initiative is well under way, with the Western Hemisphere certified as being polio-free and more than one year having passed since polio cases occurred in the Western Pacific Region of the World Health Organization. A review of the technical feasibility of eradicating other diseases preventable by vaccines currently licensed for civilian use in the United States indicates that measles, hepatitis B, mumps, rubella, and possibly disease caused by Haemophilus influenzae type b are potential candidates. From a practical point of view, measles seems most likely to be the next target. Global capacity to undertake eradication is limited, and care must be taken to ensure that a potential measles eradication effort does not impede achievement of polio eradication. Even in the absence of eradication, major improvements in control are both feasible and necessary with existing vaccines. New and improved vaccines may give further possibilities of eradication in the future. Eradication represents the ultimate in sustainability and social justice.

Although immunization rates among children are rising across the country, rates in inner-city areas have remained at ∼50%–60%, ≤30% lower than corresponding suburban or state immunization levels. The failure to raise immunization levels in poor, underserved populations is caused in part by the lack of timely and accurate child-specific immunization information for providers and parents. Immunization registries are a new tool in health care that can be used to address these and other barriers to effective immunization delivery. Moreover, immunization registries have the potential to help health care officials track and improve delivery for a broad range of important child health services. An immunization registry is a computerized database of information on children (usually preschool-age children) in a defined population (e.g. those enrolled in a health maintenance organization or living in a specific geographic area), which is used to record and track all immunizations received by each child. The registry receives the information primarily from public and private providers that administer immunizations, as well as from parents, schools, and other agencies. A fully functioning immunization registry can be used to identify individual children in need of immunizations and to report on immunization rates by population characteristics such as child age, assigned provider, or geographic area (e.g. neighborhood, city). Today, >250 local public health departments have immunization registries that are in various stages of planning or development. Only a small number of these registries meet the minimum functional criteria of maintaining records on 95% of all eligible 2-year-old children in the target population and providing an electronic immunization record that is accessible to providers. Nascent immunization registries represent innovative technologic solutions to the challenge of monitoring health problems and health care access on a population basis. This is a fundamental activity of public health agencies, but one that is increasingly shared by large health maintenance organizations. The study of the development of immunization registries across the United States provides an important case study for how public health agencies will use the rapidly developing health information infrastructure to perform health assessment and health assurance activities in a managed care environment.

This paper begins with a review of the problem of teen pregnancy in the United States. Domestic trends are compared with those of other developed countries. Antecedents of the problem are discussed. New developments in addressing the problem are then described, including the following: (a) a renewed emphasis on abstinence on the one hand; (b) a move toward a more positive view of teen sexuality on the other; (c) the development of new prevention initiatives such as STD/HIV/AIDS prevention programs, community-wide teen pregnancy prevention collaboratives, broad-based youth development programs, and state and local government initiatives; and (d) the lauching of the National Campaign to Prevent Teen Pregnancy. An analysis of the different ways in which the problem can be framed and the implications for solutions of the problem follow. Examples of promising teen pregnancy and STD/HIV/AIDS prevention programs are provided. The paper ends with a recommendation for an eclectic approach to framing the problem and possible solutions.

The environment can be thought of in terms of physical and social dimensions. The social environment includes the groups to which we belong, the neighborhoods in which we live, the organization of our workplaces, and the policies we create to order our lives. There have been recent reports in the literature that the social environment is associated with disease and mortality risks, independent of individual risk factors. These findings suggest that the social environment influences disease pathways. Yet much remains to be learned about the social environment, including how to understand, define, and measure it. The research that needs to be done could benefit from a long tradition in sociology and sociological research that has examined the urban environment, social areas, social disorganization, and social control. We summarize this sociological literature and discuss its relevance to epidemiologic research.

Over the past 30 years, health status assessment methods for adults have proliferated. Numerous generic, disease-specific, and preference-based measures now exist that tap diverse aspects of functioning, well-being, symptom states, and subjective perceptions of health. The evolution of the state of the art in adult health status assessment is reviewed. Applications of these tools in health services research, health policy, and clinical practice are discussed. Recommendations are offered for selecting among the armamentaria of tools. Conceptual and methodological challenges that confront instrument users and developers alike are identified and discussed.

This paper describes the key methodological and substantive findings of Patient Outcomes Research Teams, the first outcomes and effectiveness research centers funded by the Agency for Health Care Policy and Research. Patient Outcomes Research Teams contributed to our increased understanding of how to perform meta analysis on nontrial data, use administrative data to characterize patterns of care, develop general and disease-specific outcome measures, and disseminate important outcome information to patients and physicians to reduce practice variation. Patient Outcomes Research Teams also influenced the development of outcomes measurement in the private sector.

Research on pharmacy benefit management companies focuses on descriptive accounts of the organizations and the scope of their services. This review provides a critical analysis of publicly available research on contemporary issues surrounding the operations and effects of pharmacy benefit management companies. There has been very little systematic, empirical research on these issues; major questions concerning the impact of pharmacy benefit management companies on quality, costs, and patient outcomes remain unanswered. We analyze what is known and what needs to be known, and we explore major research challenges that lie ahead in the assessment of the pharmacy benefit management company's role in the health care system and in improving the public's health.