Islamset - Measuring the Needs

Dr Darnton-Hill has performed a singular service by calling attention to many features of population aging and its implications for individual aging. He reviews a wide variety of psychosocial and health relationships that have been uncovered in empirical studies of older persons. However, these studies are often subject to methodological deficiencies that make it difficult to assess their reliability and validity. My own experience suggests that one can generalize only to a very limited extent from many of the conclusions they reach.

What the review makes clear is that there is a pressing need for systematic cross-national, population-based research that can begin to answer the types of questions that Dr Darnton-Hill raises. Research is needed in developed as well as developing countries, where the tempo of demographic change has been accelerating.

Such research should have several important characteristics. First, it should involve the use of sufficiently large and representative scientific samples to capture the important socioeconomic and environmental diversity that exists in most countries. Second, the research should ideally be longitudinal in design, in order to assess the causal pathways involved in the aging process. Many of the cross-sectional relationships that are reported between successful aging and its determinants are confounded by selection effects that have eliminated the frail. Longitudinal studies make it possible to examine transitions in health status.

Clinical assessments, in my view, are vital in determining the relative health and physical and cognitive functioning of older persons.

and well-being, as well as the important role of interventions. Third, multidimensional research is necessary to capture the many psychosocial, health and environmental factors in the aging process. As Dr Darnton-Hill suggests, these should properly include measures of autonomy, quality of life and social integration. It should be acknowledged that these concepts are extremely difficult to define, apply and measure reliably, especially as they are related causally to morbidity and functional limitations. Clinical assessments, in my view, are vital in determining the relative health and physical and cognitive functioning of older persons. Finally, multivariate analyses are crucial to evaluate the relative importance of variables in structural equation modelling of relationships.

Many of these approaches form the basis for WHO's ongoing project on the determinants of healthy aging. With support from the us National Institute on Aging, this coordinated project has recently completed a series of pilot studies in Costa Rica, Jamaica and Thailand. This work can provide a sound basis for the multinational research that is envisioned in the WHO programme on Aging and Health.

Many of the important points presented in the review revolve around the issue of the extent to which prolonged life expectancy has been accompanied by increased years of active life. The concept of active life expectancy, measured in various ways as years of disability-free expectancy or as years of perceived healthy life (more subjectively determined), has been a central focus of the International Healthy Life Expectancy Network (REVES). Participants in the Network have been meeting periodically since 1989 to achieve standardized concepts, research designs, operational instruments and analytic measures for coordinating national time-series evaluations and cross-national evaluations. Findings to date are surprisingly positive and suggest for many countries that active life expectancy has kept pace with the gains in life expectancy. Moreover, in such countries as the United States, improvements appear to be driven by cohort changes in educational attainment and economic resources, as well as the adoption of devices and housing modifications which reduce the ill effects of disability.

The validity of these findings in the USA is being further assessed by results from recent longitudinal research, but in the meantime the approach provides an important means of monitoring health and health promotion developments. Aggregate summary measures of active life expectancy, measured at birth and at specified ages, have already been suggested as a means of setting goals for the United States Healthy People 2000 Program and WHO's Health for All by the Year 2000 initiative. They were also used in the OECD Health Systems review in 1993.

Some interesting points are raised about health promotion strategies for older persons. While I agree with many of the points that Dr Darnton-Hil1 makes about primary (individual) prevention, we must also recognize that health care systems need to be attuned to the inevitable growth in demand for geriatric medical services and long-term care. The provision of such services also affects the quality of life of older persons.

Dr Darnton-Hil1 has wisely raised a number of important points about the current state of knowledge about older persons and the factors that affect their quality of life. It is important, in my view, to emphasize the crucial role that sound research plays in improving the health and well-being of older persons. We are fortunate that a solid basis for such research has been established by recent efforts of WHO and its regional offices, the International Healthy Life Expectancy Network and the international activities of the US National Institute on Aging.