Global Health and Aging

The transition from high to low mortality and fertility—and the shift from communicable to noncommunicable diseases—occurred fairly recently in much of the world. Still, according to the World Health Organization (WHO), most countries have been slow to generate and use evidence to develop an effective health response to new disease patterns and aging populations. In light of this, the organization mounted a multicountry longitudinal study designed to simultaneously generate data, raise awareness of the health issues of older people, and inform public policies.

The WHO Study on Global Ageing and Adult Health (SAGE) involves nationally representative cohorts of respondents aged 50 and over in six countries (China, Ghana, India, Mexico, Russia, and South Africa), who will be followed as they age. A cohort of respondents aged 18 to 49 also will be followed over time in each country for comparison. The first wave of SAGE data collection (2007-2010) has been completed, with future waves planned for 2012 and 2014.

In addition to myriad demographic and socioeconomic characteristics, the study collects data on risk factors, health exams, and biomarkers. Biomarkers such as blood pressure and pulse rate, height and weight, hip and waist circumference, and blood spots from finger pricks, are valuable and objective measures that improve the precision of self-reported health in the survey. SAGE also collects data on grip strength and lung capacity and administers tests of cognition, vision, and mobility to produce objective indicators of respondents’ health and ability to carry out basic activities of daily living. As additional waves of data are collected during these respondents’ later years, the study will seek to monitor health interventions and address changes in respondents’ well-being.

Figure 10. Overall Health Status Score in Six Countries for Males and Females: Circa 2009

Notes: Health score ranges from 0 (worst health) to 100 (best health) and is a composite measure derived from 16 functioning questions using item response theory. National data collections con- ducted during the period 2007-2010.
Source: Tabulations provided by the World Health Organization Multi-Country Studies Unit, Geneva, based on data from the Study on global AGEing and adult health (SAGE).

A primary objective of SAGE is to obtain reliable and valid data that allow for international comparisons. Researchers derive a composite measure from responses to 16 questions about health and physical limitations. This health score ranges from 0 (worst health) to 100 (best health) and is shown for men and women in each of the six SAGE countries in Figure 10. In each country, the health status score declines with age, as expected. And at each age in each country, the score for males is higher than for females. Women live longer than men on average, but have poorer health status.
The number of disabled people in most developing countries seems certain to increase as the number of older people continues to rise. Health systems need better data to understand the health risks faced by older people and to target appropriate prevention and intervention services. The SAGE data show that the percentage of people with at least three of six health risk factors (physical inactivity, current tobacco use, heavy alcohol consumption, a high-risk waist-hip ratio, hypertension, or obesity) rises with age, but the patterns and the percentages vary by country (Figure 11). One of SAGE’s important contributions will be to assess how these risk-factor profiles affect current and future disability. Smaller family size and declining prevalence of co-residence by multiple generations likely will introduce further challenges for families in developing countries in caring for older relatives.

Figure 11. Percentage of Adults with Three or More Major Risk Factors: Circa 2009

Notes: Major risk factors include physical inactivity, current tobacco use, heavy alcohol consump- tion, a high-risk waist-hip ratio, hypertension, and obesity. National data collections conducted during the period 2007-2010.
Source: Tabulations provided by the World Health Organization Multi-Country Studies Unit, Geneva, based on data from the Study on global AGEing and adult health (SAGE).