Changes of inequality in functional disability of older populations in China from 2008 to 2018: a decomposition analysis

Background: This study aims to determine the change of inequality in functional disability of older populations in China over the period from 2008 to 2018 and decompose the contribution of the personal and environmental predictors to the change. Methods: Data were drawn from two waves (2008 and 2018) of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Functional disability was assessed by the basic activities of daily living (ADL) and the instrumental activities of daily living (IADL). Concentration index (CI) was calculated to measure the socioeconomic inequality in ADL and IADL. A two-level linear regression model was established to identify the individual and care environmental predictors and their contribution to the inequality of ADL and IADL, respectively. The Oaxaca-type decomposition technique was adopted to estimate the contribution of these predictors to changes of the inequality in ADL and IADL over the period from 2008 to 2018. Results: Socioeconomic inequality in functional disability of older adults increased over the period from 2008 to 2018, with the CI for ADL changing from − 0.0085 to − 0.0137 and the CI for IADL changing from − 0.0164 to − 0.0276, respectively. Self-rated economic status was the single most powerful predictor of changes in the inequality, although the growing and dominant rating of older persons with fare economic status could offset the detrimental effects of other (rich or poor) ratings on the changes. The enlarged inequality was also attributable to the increasing importance of regular exercise and its distributional changes, as well as the accumulative long-term effect of farming in earlier life. They outweighed the counteracting effects of rural residency, living with chronic conditions and in an institution. Conclusions: Socioeconomic inequality in functional disability of older populations in China increased over the period from 2008 to 2018. Re-distribution of wealth remains to be a powerful instrument for addressing the inequality issue, but alone it is not enough. The detrimental accumulative effect of farming will not disappear any time soon. While rural residents are catching up with their urban counterparts, new challenges such as physical inactivity are emerging.