Date Presented 03/31/2022

The purpose of this study was to develop a scale that can measure the cognitive and physical functions of older adults in China, Japan, and Korea and to compare the health function across the three Asian countries. Scale anchoring with Rasch modeling was performed using three aging panel survey databases to obtain 13 cognitive function items and 20 physical function items. The study findings showed that Japan had the highest physical and cognitive functions of the three countries.

Primary Author and Speaker: Nam Sanghun

Additional Authors and Speakers: Suyeong Bae, Ickpyo Hong

PURPOSE: Currently, the burden of diseases due to aging is increasing, and accordingly, many public health policies for the cognitive and physical health of the older adults were being implemented (Chang et al., 2017). Such public health policies can understand the factors of success or failure through cross-national comparisons on the cognitive and physical health of the older adults (Lee et al., 2018). In contrast to the previous studies that comparing North America and Europe, there are a few studies that compare the health status of older adults between Asian countries (Nakagawa et al., 2020). Among East Asian countries, China, Japan, and Korea are geographically close and have similar cultures, making them suitable for comparing cognitive and physical functions (Yoon, Kim, & Kim, 2013). Therefore, this study intends to develop the equating measurement scale using the aging panel survey data of three countries and compare the health status between countries.

DESIGN: A retrospective cohort study design. The study databases included the China Health and Retirement Longitudinal Study (CHARLS) in China, the Japanese Study on Aging and Retirement (JSTAR) in Japan, and the Korean Longitudinal Study of Aging (KLoSA) in Korea. We selected and extracted only the survey participants who having heart disease and stroke, and extracted 2,506 people from China, 178 people from Japan, and 934 people from Korea. The mean age of the Chinese sample was 62.47 (SD = 10.04) years old, 63.38 (SD = 6.22) years old in Japan, and 70.07 (SD = 8.92) years old in Korea.

METHOD: A total of 19 cognitive function items and 29 physical function items were extracted from the three national survey databases. First, nine common items of the cognitive (n = 4) and physical function (n = 5) were extracted. Principal Component Analysis (PCA) of the Rasch residuals was used to examine the unidimensionality assumption of the nine common items. Rasch analysis was used to test the item fit and differential item functioning (DIF) of the nine common items. Lastly, the finial cognitive and physical function item sets were created by anchoring the nine common items to all items. Analysis of variance was used to compare the cognitive and physical functions across the three countries.

RESULTS: The PCA of the Rasch residuals indicated that the common cognitive function items (eigenvalue = 1.60) and common physical function items (eigenvalue = 1.51) were unidimensional. The common items of cognitive function and physical function showed acceptable item fit statistics; however, there was DIF in bathing, toilet use, continuous subtraction, and word input items. By anchoring common items to all cognitive and physical functions, 13 cognitive functions and 22 physical functions were finally selected. The cross-national comparisons indicated that Japan had the highest cognitive and physical functions compared to the other countries.

CONCLUSION: The development of equating items can measure the cognitive and physical functions of the three East Asian countries. This measurement made it possible to compare the health function of the three countries.

IMPACT STATEMENT: Comparing health functions in different countries using the same measurement tool allows comparison of health among older adults without being limited to one country. This helps to identify factors that influence the success or failure of cross-national public health policies.


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Chang, A. Y., Skirbekk, V. F., Tyrovolas, S., Kassebaum, N. J., & Dieleman, J. L. (2019). Measuring population ageing: an analysis of the Global Burden of Disease Study 2017. Lancet Public Health, 4(3), e159-e167.

Nakagawa, T., Cho, J., & Yeung, D. Y. (2020). Successful aging in East Asia: comparison among China, Korea, and Japan. Journals of Gerontology: Series B, 76(Suppl. 1), S17-S26.

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