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Institute of Medicine (US) Committee on Summary Measures of Population Health; Field MJ, Gold MR, editors. Summarizing Population Health: Directions for the Development and Application of Population Metrics. Washington (DC): National Academies Press (US); 1998.

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Summarizing Population Health: Directions for the Development and Application of Population Metrics.

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APPENDIX BOverview: Workshop on Summary Measures of Population Health Status

Marthe Gold, M.D., M.P.H.

City University of New York Medical School


Summary measures of health include an array of descriptors that are intended to create an understanding of the well-being of populations. The groups they describe may range from patients in clinical trials to representative samples of communities or nations. The descriptors can be as rough as mortality rates, or may be more finely tuned, describing most aspects of commonly shared understandings of the components of health. For example, there is wide consensus that physical functioning, mental and emotional well-being, social and role functioning, general health perceptions, pain, energy, and vitality as a core set of concepts are central in conceptualizing health. 1 At this meeting, presentations and discussions will focus on the types of summary indicators that are variously referred to as “health status,” “health-related quality of life,” and “functional status” measures. They share the common purpose of informing a wide range of decision making in the public health and medical systems both in the United States and abroad.

More specifically, it has been proposed that health status measures are suited to measuring the efficiency or effectiveness of medical interventions, assessing quality of care, estimating the needs of populations, improving clinical decisions, and understanding the causes and consequences of differences in health. 2 Framing their uses in a slightly different way, Bergner and Rothman 3 have suggested that health status assessment measures serve four different functions, including examination of the health of general populations, clinical interventions and their effects, changes in the health care delivery system, and health promotion activities and their effects.

In addition to capturing a picture of health at a point in time, some summary measures are designed to allow the incorporation of information about projected life expectancy, thereby allowing estimates of both the quality and the quantity of life that is associated with health care interventions. Health-Adjusted Life Expectancies (HALEs), Quality-Adjusted Life Years (QALYs), Years of Healthy Life (YHLs), and Disability-Adjusted Life Years (DALYs) integrate health status with survival. All of these measures attach a single number, ranging from 0 (death) to 1.0 (optimal health), to a complex of social and personal attributes that represent health status. That number is then linked to life expectancy and combined into a one-dimensional measure of overall health. Although they have been generated for use in slightly different contexts, (for example, the QALY has been used primarily to study the cost-effectiveness of medical treatments, 4 the DALY to measure the burden of disease worldwide, 5 and the YHL to track the health of the U.S. population, 6 in measuring the aggregate health of defined populations, HALEs, QALYs, DALYs, and YHLs are all suited to making comparative assessments of the health needs of populations. In addition, they share the potential for evaluating the effects and performance of different types of health programs.

As we shall hear in more detail during this meeting, there is growing interest at international, federal, and state levels in using these measures to guide prioritization of health care investments. Within the U.S. health care policy arena, QALYs were used in the Oregon Medicaid Demonstration project to develop a list of priority services for which full coverage would be available to all Oregonians. 7 DALYs were initially applied in the context of developing priorities for resource investments in health within the developing world. 8 YHLs, HALEs, and a variation on DALYs have been used, respectively, at the federal level within the United States, in Canada, and in the Netherlands to describe the overall health of nations. The Health Care Financing Administration (HCFA) of the U.S. Department of Health and Human Services (DHHS) is exploring the longitudinal use of one health status measure, the SF36, 9 to track outcomes at the clinical care level. Although the SF 36 is not designed to be combined with survival information, the intent of the tracking parallels other efforts being conducted using combined measures.

There are a number of arenas where summary measures are being used to assess the health of populations. In general, however, these metrics are not in wide use at the policy level. Despite a 25-year history of development and fine-tuning, summary measures are most frequently used and cited by the research community that has created them. Discussion of the merits and demerits of summary measures has been conducted primarily among philosophers and methodologists. Application at the delivery and program evaluation side of health care has lagged substantially behind the general public health tracking function.

The reasons for the disconnect between the measurement and the policy communities are many. Most obviously, busy policy makers often are not aware of these techniques. A wider effort to inform decision makers about the range of uses of summary measures is required and we hope that this meeting and the committee's report will contribute to this effort and help familiarize different interests with the potential opportunities created by the measures. It is also true, however, that many decision makers are at least glancingly aware of the opportunities that summary measures create in informing policy, but are reluctant to use them because methodological and ethical concerns they feel have been inadequately addressed to date.

For example, on the methods side, summary measures capture a continuum of components of health which may not have credibility to all constituencies. Some measures harvest information directly from patients regarding their mental health, symptoms, and physical, social, and role function; they are designed to provide information at the clinical care level. Others capture the judgments of health experts about the health states associated with particular diseases or conditions with the goal of capturing snapshots of disease burden in large populations. This type of summary measure may not always capture what is most salient to decision makers and their constituencies as they consider priorities for resource allocation.

Other concerns may arise from the differential sensitivities that measures have in recording decrements in particular aspects of health. For example, a measure that includes information only on pain and physical function may paint a far harsher picture of arthritis than of some types of cancer, thereby giving pause to those who see this as a type of bias built into the measurement strategy. It is well known that QALYs are constructed from many different kinds of summary measures of health-related quality of life. 10 These measures comprise different domains of health and use different scoring strategies to value the health states, resulting in wide variations in scores for similar conditions. Decision makers may be legitimately concerned about the results from different evaluations using measures that do not readily translate to one another.

On the ethics side, decision makers may be aware of, and not fully comfortable with, the utilitarian,” “greatest good for the greatest number” perspective that is fundamental to the assessment of gain used in the current QALY model. It is the sum of the QALYs produced by an intervention that measures the desirability of the intervention; it does not matter to whom the QALYs accrue. Life-saving programs or therapies for persons with relatively low health-related quality of life, or for older persons, may produce far fewer QALYs than would interventions that are primarily health status improving. Therapies with a small health status enhancing impact on large numbers of persons, for example a cure for the common cold, can confer far more QALYs than those that save the lives of a few people with a rare disease. Concerns about how one accounts for distributive justice—helping those in most need first, or placing priority on life-saving rather than quality-enhancing procedures—and whether these measures are in fact discriminatory, are likely areas of discomfort within the policy community. Finally, many of the measures rely on assessments of peoples' values for differing levels of health. There is a good deal of controversy about whose values are most appropriate to capture in judgments about health states. For example, there are known differences between the values people who have experience with a disease bring to the assessment of that disease compared to a general population. In addition, there are gaps in information as to what impact sociodemographic variables such as social class, culture and ethnicity, and age have on assessments of health status.

The methodological and ethical issues related to the use of summary measures may be more or less important or controversial depending on the function a measure is intended to serve. For example, the Years of Healthy Life measure was intended to track trends in the U.S. population for purposes of providing an overview of the nation's health. As such, it parallels economic indicators such as the Gross Domestic Product (GDP) which provides a snapshot of economic functioning without implying a particular direction for action. Snapshot indicators increase or decrease or remain the same; this overview can provide useful information to a nation or a region about trends in health. Although analysts can attempt to identify the specific variables responsible for changes in the summary indicators, the indicators themselves do not suggest specific policies or actions. On the other hand, measures intended to capture the impact and performance of particular interventions (e.g., coronary artery bypass grafting), or particular health systems, (e.g., a managed care plan), would reasonably be held to higher levels of performance. The outcomes charted by these measures might suggest to planners and decision makers a need to expand or abolish access to therapies or programs which have importance to different constituencies.


This workshop will focus on summary measures of health status and health-related quality of life that have been created to serve a number of informational and decision making needs in both medicine and public health. The extent to which these measures accomplish performance and tracking objectives in health and the areas where they need further refinement are important issues for health care decision makers. Workshop participants are methodologists, ethicists, and decision makers from the public and private sectors, in the United States and abroad. The public health and the medical care delivery systems are both represented.

Day 1

Members of the first panel will focus on applications of these measures in policy-relevant settings. Presenters will describe the nature of their evaluation requirements and the measurement strategy they have used to accomplish them. Work in tracking the health of the U.S. population will be presented by Ed Sondik, Director of the National Center for Health Statistics. Louise Gunnig, from the Netherlands, and Michael Wolfson, from Statistics Canada, will describe their respective efforts in developing these measures to track and prioritize population health in their countries. Paige Sipes Metzler, who worked with the Oregon Health Services Commission, will describe use of QALYs in state-level decision making on the components of a basic health care benefit package. Jim Mark, Director of the Center for Chronic Diseases at the Centers for Disease Control and Prevention, will discuss CDC's initiative to assess burden of disease in a manner that creates opportunities for exploring prevention priorities for the United States. Howard Seymour will provide an account of the use of these measures at a local health planning level in the United Kingdom.

The next series of presentations will look more closely at the methods used to build these measures. The intent here is to provide all workshop attendees with a working understanding of the different aspects of health and disability that are captured by these measures, the manner in which these aspects are aggregated (or not) to provide a composite number that represents a state of health, and the different techniques for integrating the health status numbers with life expectancy. Dennis Fryback will provide an overview of health status measurement, describing differences between measures that incorporate peoples' values for health states and those that do not and how different measures can be used to fashion health-adjusted and quality-adjusted life expectancies. Chris Murray will describe a particular subset of quality-adjusted life expectancy, the Disability-Adjusted Life Year, commenting on its intended uses and data requirements.

These papers will be followed by presentations from Dan Brock and Norman Daniels who will focus on a number of the ethical issues that have been raised by the use of QALYs and DALYs. Dan Brock's comments will be directed toward exploring some of the ethical assumptions that are contained within the actual methodology. Norman Daniels will explore the issues of distributive justice that arise within resource allocation decision making, and the degree to which these measures both solve and create problems for decision makers.

Central objectives of this conference are to gather careful input from the policy community regarding directions for further developmental work in methods and ethics, and to explore the potential for broader use of summary measures in decision making. A series of questions, noted below, have been developed to focus small group discussions on the second day of the conference. The final session of the first day of the workshop will include comments from decision makers who have begun to examine how they can best use summary measures in their work settings. They will reflect on a number of the questions in the context of their own planning and policy needs. Bruce Fried and Jeff Kang from the Center for Health Plans and Providers will discuss HCFA's interest in, and use of, the Health of Seniors' measure for plan accountability with regard to health outcomes. Barbara DeBuono, Commissioner of Health for New York State, will comment on the relevance of these measures at the state level, in an array of programs ranging from managed care to public health. Jean-Pierre Poullier, from the Organization for Economic Cooperation and Development, will describe international discussions under way to achieve consensus concerning the use of summary measures for shared economic evaluations. Stephen Safyer will reflect on how a large, multifaceted health care delivery system providing a continuum of care from primary care to tertiary care, to rehab and nursing home, views the use of these measures. Finally, John Eisenberg, director of the Agency for Health Care Policy and Research (AHCPR) in the U.S. Department of Health and Human Services, will describe research and applied uses for these measures including cost-effectiveness analyses of new technologies and therapies and evaluation of plan performance and potential for use in risk-adjustment of premiums for enrollees in managed care organizations.

Day 2

The second day of the meeting will involve deliberations in small, pre-assigned working groups. Group assignments reflect the experiences and needs of conference participants in the use of these measures in diverse decision-making contexts. In addition, to technically clarify some of the issues under discussion, each group has representation from the methodology and philosophy communities. A facilitator and a rapporteur, who is a member of the IOM committee, are assigned to each of the working groups. The rapporteur will bring the groups' discussions back to the larger meeting, and to the deliberations of the committee.

The questions below will form the nidus for the discussion in the morning small group sessions. We hope that early review of and reflection on these questions both prior to the meeting and during the presentations of the first day will aid members of the working groups in providing guidance to the committee in a number of different areas including direction for:

  • development of the methodology,
  • further exploration of ethical issues, and
  • possible applications of summary measures.

On the afternoon of the second day, the full group will reconvene for presentation and discussion of the summarized deliberations of each work group.


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Copyright 1998 by the National Academy of Sciences. All rights reserved.
Bookshelf ID: NBK230304


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