SAGE Waves 0, 1, 2 & 3
The WHO Evidence, Measurement and Analysis unit (formerly the Multi-Country Studies unit) developed the Study on Global AGEing and Adult Health (SAGE) as part of an ongoing program of work to compile comprehensive longitudinal information on the health and well-being of adult populations and the ageing process. The core SAGE collects data on adults aged 18+ years, with an emphasis on populations aged 50+ years, from nationally representative samples in six countries: China, Ghana, India, Mexico, Russian Federation and South Africa.
Household and individual level micro- and meta-data, along with survey materials, are available from:
- SAGE Wave 0 (2002–2004)
- SAGE Wave 1 (2007–2010)
- SAGE Wave 2 (2014/15)
- SAGE Wave 3 (2018/19)
Interest in running future waves of SAGE in the five partner countries, and new survey countries should be directed to the HH health survey team in WHO (sagesurvey@who.int).
SAGE Wave 0: 2002–2004
A baseline cohort was created during the 2002–2004 World Health Survey (WHS) based on nationally representative sampling frames to select adults aged 18 and older for interview. A total of 70 countries implemented the WHS, including the six SAGE countries: China, Ghana, India, Mexico, Russia and South Africa. For these six countries, this round of data collection is also labelled, SAGE Wave 0.
Face-to-face interviews were used to generate a dataset containing 63 445 adults aged 18 years and older, including 18 883 persons aged 50 years and older, in the six SAGE Wave 0 countries.
Sample sizes
All samples were selected from nationally representative frames with a known probability in order to obtain estimates based on general population parameters. The sample sizes drawn were based on feasibility and survey costs. The resulting sample sizes ranged from almost 39 000 in Mexico to 2400 in South Africa.
| China | 3 993 |
| Ghana | 3 938 |
| India | 9 994 |
| Mexico | 38 746 |
| Russian Federation | 4 422 |
| South Africa | 2 352 |
Sample sizes background characteristics by country (weighted) (PDF)
Survey materials
In order to enhance the utility of the World Health Survey, its development, testing and implementation used a modular survey instrument. The intention is that each module may be used as a standalone product in a variety of household survey contexts – and that collaborating countries could select the combination of modules to include based on the policy needs. The standard modules are listed below.
Household questionnaire
- Roster of all the individuals in the household
- Household health intervention coverage
- Health insurance
- Health expenditure
- Indicators of permanent income
- Health occupations
Individual questionnaire
- Socio-demographics
- Health state description
- Health state valuation
- Risk factors
- Mortality
- Coverage of health interventions
- Health system responsiveness
- Health system goals and social capital
- Interviewer observations
Download questionnaires and supporting materials:
Summary of measures included in questionnaires (PDF)
WHO World Health Survey web pages
WHO World Health Survey data catalog
Data access
Wave 0 meta- and micro-data, using DDI standards, are available through the online SAGE Data Archive at no cost: to access it, choose “Filter by Topic”; select “World Health Survey (WHS)”, click on country/data of interest, then click on "Microdata request form", and follow the online instructions to obtain data.
Access the online SAGE Data Archive
Support
The World Health Survey was supported by World Health Organization.
Health statistics and information systems
SAGE Wave 1: 2007–2010
Implementation of SAGE Wave 1 was from 2007 to 2010 in six countries over different regions of the world (China, Ghana, India, Mexico, Russian Federation and South Africa). The study design included samples of follow-up respondents from Wave 0 in four countries (Ghana, India, Mexico and Russia) and new respondents in all countries.
SAGE Wave 1 used two target populations: a large sample of persons aged 50 years and older, which is the focus of the study, and a smaller comparative sample of persons aged 18–49 years. In all countries, households were classified into one of these two mutually exclusive categories: one or more persons aged 50 years and older are selected from households classified as “50+ households” and one person aged 18–49 years from a household classified as an “18–49 household”. In the older households, all persons aged 50 years and older (for example, spouses and siblings) were invited to participate. Proxy respondents were identified for respondents who were unable to respond for themselves (for cognitive issues, decisions based on the IQ Code (Jorm 1989)).
Sample sizes
All six countries implemented a multistage cluster sampling design resulting in nationally representative cohorts. Household-level analysis weights and person-level analysis weights, which included sample selection and a post-stratification factor, were calculated for each country. Post stratification used the most recent estimates provided by the national statistical offices of the respective countries.
In consultation with the Ministry of Health in China, China CDC and Shanghai CDC, a new sampling design was used for SAGE in China drawn from an existing national surveillance system. In India, a representative sample of six States was included, taking into consideration population size and level of development, and can be modelled to a nationally representative sample. The Russian Federation's sample was extended to the east and south (as compared to the Wave 0 sample) to include respondents from the Asian and Southern European regions of the country. The South African team chose to select a new sample based on an updated sampling frame from Wave 0.
| China* | 14 813 |
| Ghana | 5 110 |
| India** | 11 230 |
| Mexico | 2 756 |
| Russian Federation | 4 355 |
| South Africa* | 4 223 |
* The China and South Africa Wave 1 samples are new, and do not include any Wave 0 follow-up respondents.
** The India sample for Wave 1 includes a large number of women aged 18-49 years as part of a nested study, subsidized by the SAGE India team.
Sample sizes background characteristics by country (weighted) (PDF)
Survey materials
The SAGE survey instruments and methods were adapted from those used by the World Health Survey (WHS) and were informed by a review of 16 surveys on ageing (including the US Health and Retirement Survey (HRS) and the English Longitudinal Study of Ageing (ELSA).
The SAGE survey instruments assessed health status and health systems from a household and individual perspective. SAGE also evaluated perceptions of well-being and more objective measures of health, including measured performance tests: 4m timed walk; spirometry; cognitive battery (verbal fluency, immediate and delayed recall, digit span forward and backward); near and distance vision; and, grip strength; and biomarkers: blood pressure and pulse rate; height and weight; hip and waist circumference; and, blood spot from finger prick.
Standardized SAGE survey instruments were used in all countries consisting of five main parts: 1) household questionnaire; 2) individual questionnaire; 3) proxy questionnaire; 4) verbal autopsy questionnaire (VAQ); and, 5) appendices including showcards. A VAQ was completed for deaths in the household over the last 24 months. The procedures for including country-specific adaptations to the standardized questionnaire and translations into local languages from English follow those developed by and used for the WHS.
SAGE Wave 1 survey materials can be downloaded by clicking on the links below, including the generic household, individual and proxy questionnaires, the verbal autopsy and Survey Manual.
Download questionnaires and supporting materials:
- Summary of measures included in questionnaires pdf, 148kb
Country-specific adaptations for SAGE questionnaires and data are available upon request by e-mail at sagesurvey@who.int.
Data access
Wave 1 meta- and micro-data, using DDI standards, are available through the online SAGE Data Archive at no cost: to access it, choose “Filter by Topic”; select “Study on Global Ageing and Adult Health (SAGE)”, click on country/data of interest, then click on "Microdata request form", and follow the online instructions to obtain data.
Access the online SAGE Data Archive
Support
Support for SAGE Wave 1 was provided by the U.S National Institute on Aging (NIA) Division of Behavioral and Social Research (BSR) through Interagency Agreements (OGHA 04034785; YA1323–08-CN-0020; Y1-AG-1005–01) with WHO. WHO provided salary support for members of the WHO SAGE team. The Governments of China and South Africa provided additional financial support for implementing the survey in their respective countries.
SAGE Wave 2: 2014/15
Implementation of the full SAGE Wave 2 follow-up was completed in China, Ghana, India, Mexico, Russian Federation and South Africa by the end of 2015. - Data release was delayed due to considerable technical issues with the CAPI program and programmers.
Sample sizes
SAGE maintained its two target populations: a large sample of persons aged 50 years and older which is the focus of the study and a smaller comparative sample of persons aged 18-49 years. This wave "aged-in" follow-up respondents to the 50+ and had replacements for losses to follow-up in each country to maintain the sample sizes. Efforts were made to increase the sample size and improve response rates in Mexico compared to Wave 1.
| China | 17 920 |
| Ghana | 4 704 |
| India | 9 093 |
| Mexico | 4 665 |
| Russian Federation* | pending |
| South Africa | 3 153 |
*Negotiations are ongoing with the SAGE Russia team about data integrity and Russian legislation in accordance with the Council of Europe Convention for the Protection of Individuals with regard to Automatic Processing of Personal Data as of 01 Sep 2015.
Survey materials
The psychometric properties of the standardized SAGE survey instruments were re-examined, and questionnaires revised for pilot testing. Pilot test results (first 100 interviews) were reviewed for feedback prior to full implementation of Wave 2. The final questionnaires and survey materials are available on the (WHO data archive).
Country-specific adaptations for SAGE questionnaires and data will be made available on request through sagesurvey@who.int.
Data users agreement
The USC Center for Economic and Social Research (CESR) was engaged to develop the CAPI in MMIC. Mexico used their own CAPI system.
Support
Support for SAGE Wave 2 was provided by WHO and the Division of Behavioral and Social Research at the US National Institute on Aging, through Interagency Agreements (OGHA 04034785; YA1323-08-CN-0020; Y1-AG-1005-01). As with previous waves, additional in-kind and financial support from countries was needed, with support from Ministry/Departments of Health. The University of Ghana provided in-kind and financial support for SAGE Ghana Wave 2.
SAGE Wave 3: 2018/19
Wave 3 follow-up was completed in 2018/19 in China, Ghana, India, Mexico and South Africa.
Sample sizes
SAGE maintained its two target populations: a large sample of persons aged 50 years and older which is the focus of the study and a smaller comparative sample of persons aged 18-49 years. This wave "aged-in" follow-up respondents to the 50+ and had replacements for losses to follow-up in each country to maintain the sample sizes.
| China | 8 614 |
| Ghana | pending |
| India | pending |
| Mexico | pending |
| Russian Federation* | N/A |
| South Africa | pending |
Survey materials
The standard SAGE survey instruments were again reviewed following Wave 2 and used as the basis for Wave 3. The Wave 3 questionnaire was shortened considerably. The questionnaires and survey materials will be available on the (WHO data archive).
Country-specific adaptations for SAGE questionnaires and data will be made available on request through sagesurvey@who.int.
Data users agreement
Data will be accessible through the (WHO data archive)
Support
Financial support for Wave 3 came from WHO and the Division of Behavioral and Social Research at the US National Institute on Aging, through NIH Grant R01AG034479 and Interagency Contract HHSN271201300066C to enhance data comparability, to implement SAGE Wave 3 in five countries.
After the Wave 3 round of data collection, future waves of SAGE to be implemented based on country interest and support. The World Health Survey Plus (WHS+) will be another avenue for continuing SAGE through WHO's Division of Data, Analysis and Delivery for Impact.