ASSESSMENT OF HEALTH STATUS

The health status of populations and of individuals is assessed for many reasons. Assessing needs for care helps guide the allocation of resources— diagnostic assessments guide treatment, prognostic assessments contribute to planning, and assessing changes in health status is central to evaluating the quality of health care.

Because "health" is in many ways an abstract concept, it cannot easily be assessed directly. Instead, indirect indicators such as a response to a question or a clinical observation are used. These may be combined into a numerical index, very much as economists use an index to summarize the performance of the stock market. Alternatively, health indicators may be presented in the form of a profile, in which different aspects of health are presented separately, rather as a car company might present a profile of a car's performance, handling, fuel economy, and size.

There are several sources of public health indicators. For practical reasons, there is a strong preference toward using existing information wherever possible, although no single source is ideal. There is, for example, the anomaly that many health assessments are based on people who are not healthy. Examples include death certificates, hospital discharge information, and notifiable disease reports. These may be aggregated to provide statistics (such as mortality rates) at the community, regional, or national level. The advantage of mortality as an indicator of health is a practical one: Deaths must be recorded by law and represent a complete and accessible source of information. Other sources for public health assessment include rates of hospitalization or of disease. However, because an illness will not be recorded unless a person is receiving formal treatment, hospital statistics are at least partly based on the availability of care and may misrepresent the level of disease in a population. To overcome these limitations, indicators must be collected in other ways. Questionnaires and surveys, for example, are not limited to people who are seeking care and need not include only negative indicators. Positive indicators, such as fitness levels, the percentage of the population playing sports, or self-reported indicators of happiness, can also be assessed. The disadvantage to such methods is simply that these data are not routinely collected and are costly to gather. Health assessments may also include environmental indicators, such as water or air quality. These do not form direct health indicators, however, but generally refer to risk factors external to individuals that may play an explanatory role in analyzing health patterns.

Assessments reflect prevailing definitions of health. The World Health Organization, for example, views health as a resource for living. A healthy population, therefore, may be defined as one that safeguards the health of its members—the health of the population may be a resource for the well-being of its members. This introduces the idea of assessing the health of a population, rather than merely health in a population. If a population represents more than the sum of the individuals within it, public health assessments must represent more than data based solely on individuals. With this view in mind, several categories of indicators have been proposed. These include health resources, such as the existence of immunization programs; indicators of collective justice, such as the level of disparity in individual health indicators within a society; indicators of social capital (e.g., trust in one's neighbors, involvement in community activities); indicators of collective capacity, such as community participation and volunteering; indicators of resiliency, such as a population's readiness and ability to cope with challenges such as natural disasters; and functional indicators, such as a society's level of internal peace, safety, or creativity.

Approaches to assessing health are not static, but evolve in a mutual interaction with the prevailing definition of health and the health issues facing a society. From the many possible indicators of health, we tend to choose those that reflect problems of concern and for which improvement is sought. Publication of an indicator, such as the infant mortality rate, focuses attention on a particular problem, and the resulting interventions will attempt to correct it. Health assessments thus indirectly influence public health, which has the effect of reducing the value of that indicator as a marker of a current health problem. New indicators must therefore be selected, and the cycle begins again. For example, as the infant mortality rate declines, growing numbers of infants exhibit health problems associated with low birth weight or prematurity, and new assessments are needed to address these problems.

Ian McDowell

(see also: Certification of Causes of Deaths; Child Mortality; Environmental Determinants of Health; Evaluation of Public Health Programs; Health Measurement Scales; Infant Mortality Rate; Life Expectancy and Life Tables; Mortality Rates; Notifiable Diseases; Observational Studies )

Bibliography

World Health Organization (1984). Health Promotion: A Discussion Document on the Concept and Principles. Copenhagen: WHO Regional Office for Europe.

—— (1986). Ottawa Charter for Health Promotion. Copenhagen: WHO Regional Office for Europe.

Young, T. K. (1998). Population Health: Concepts and Methods. New York: Oxford University Press.