Supplementary Material for: Changes in Health Expectancy for Older Adults in Japan: Results from Two Longitudinal Surveys

Background: Although there is evidence of improvements in health expectancy among the Japanese population, existing estimates are based on the prevalence of morbidity taken from cross-sectional survey data. Objectives: This study employed a multistate life table approach to compute incidence-based health expectancy measures, namely active and inactive life expectancy (LE), for two longitudinal survey cohorts from 1990 to 2009. Methods: This study used data from two longitudinal surveys of older adults in Japan: the National Survey of the Japanese Elderly (1990–1999) and the Nihon University Japanese Longitudinal Study of Aging (1999–2009). We employed the Interpolation of Markov Chains technique to compute the number of years at age 65 years to be spent with and without difficulty in performing activities of daily living (ADLs) or instrumental ADLs. Results: We documented significant increases in active LE for men and women at age 65 years over the 10-year study period. There were significant changes in total LE for men and in the percentage of active life for women. Inactive LE did not significantly change across the two survey cohorts during the study period. Conclusions: Our results show that the health status of older adults in Japan has largely improved over the 10-year study period, with increases in both the duration of life and time spent in an active state. This finding offers evidence of compression of morbidity among older men and women in Japan.

研究背景：尽管已有证据表明日本民众的健康预期寿命有所提升，但现有估算均基于横断面调查数据中的患病率水平。研究目的：本研究采用多状态生命表方法，针对1990至2009年的两组纵向调查队列，计算基于发病情况的健康预期寿命指标，即活动自如预期寿命与活动受限预期寿命（LE）。研究方法：本研究使用了两项日本老年人纵向调查数据集：分别为1990-1999年开展的《日本老年人全国调查》（National Survey of the Japanese Elderly），以及1999-2009年的日本大学老龄化纵向研究（Nihon University Japanese Longitudinal Study of Aging）。我们采用马尔可夫链插值法，计算了65岁人群在完成日常活动（activities of daily living, ADLs）或工具性日常活动（instrumental ADLs）时，存在困难与无困难状态下的剩余生存年数。研究结果：本研究发现，在10年研究周期内，65岁男性与女性的活动自如预期寿命均出现显著增长；男性总预期寿命、女性活动寿命占比均发生显著变化。而活动受限预期寿命在两组调查队列间未出现显著变化。研究结论：本研究结果显示，在10年研究周期内，日本老年人的健康状况总体得到改善，其寿命总时长与活动自如状态的持续时间均有所延长。这一发现为日本老年群体的发病率压缩现象提供了实证依据。