healthier (or less healthy) population generates—should be measured (National Research Council, 2005, pp. 131-132).
In this chapter, we describe and assess various approaches for measuring population health (mortality and nonfatal/impairment dimensions), acknowledging that best measures may vary by purpose and for different populations along the health spectrum. We focus on generic health here, realizing that there is also interest in disease-specific indicators. Our recommendations in Chapter 6 for data collection on major chronic diseases to facilitate research on spending and health linkages would provide the data for a more detailed annual report, as recommended in the Institute of Medicine’s State of the USA Health Indicators letter report (2009).
In addition to current health status, we also consider risk factors that impact future health. Current health status does not capture the health effects of such risks as hypertension, which does not cause symptoms today but may do so in the future. In principle, these risk factors, together with age, current health, and a variety of other determinants (see Chapter 6) go into health capital (a stock of health), which can be defined as the present discounted value of future health consumption flows (Grossman, 1972). Some portion of a person’s health capital is determined genetically, but health can also be affected through investments in inputs ranging from medical care to personal behaviors, such as consumption habits and exercise. While calculating national health capital is not feasible at this time, data on some of the risk factors that go into those calculations could be collected—or, at least, data that are already collected could be extended and more systematically compiled period by period.
Monitoring the population’s health status requires metrics that combine quantity and quality of life such as quality-adjusted life years (QALYs). A number of such measures are already widely used to identify unmet health needs and to guide policies for addressing those needs. The multiplicity of measures reflects the lack of an undisputed definition of and method for measuring population health (Kindig and Stoddart, 2003; McDowell, Spasoff, and Kristjansson, 2004).
Nonetheless, some broad generalizations are possible. For the purpose of developing a health account used to evaluate productivity of direct medical and public health services, the health of a population or subgroup within the population is taken to be some combination of survival probabilities and the sum (or, equivalently, the average) of the health of survivors in the population or subgroup. Measuring the health of the population under this assumption reduces to calculating death rates, measuring the health of individual survivors, and aggregating across individuals.
The oldest and simplest measures of population health are death records. These were used, for example, to calculate the impact in excess deaths of the