The association between self-rated health and all-cause mortality and explanatory factors in China's oldest-old population.

Background: Self-rated health (SRH) is considered a condensed summary of information about bodily conditions that involves people's biological, cognitive, and cultural status, but has been under-studied in the oldest old population. This study aimed to investigate the association between SRH and all-cause mortality among the oldest-old population in China and to explore potential explanatory factors in this association. Methods: The study was based on the Chinese Longitudinal Healthy Longevity Survey (CLHLS) from 1998 to 2018 and included 30 222 participants aged 80 years or older (ie, the oldest old) in the analysis. We used Cox models to assess the association between SRH and mortality in this population and its subgroups, and used the Percentage Excess Risk Mediated approach to identify potential contributing factors. Results: After adjustment of confounders, people with "good" "neutral", and "bad/very bad" SRH were significantly associated with 8% (95% confidence interval (CI) = 3%-13%), 23% (95% CI = 18%-29%), and 52% (95% CI = 44%-61%) higher hazard of mortality respectively, compared with those with "very good" SRH. The significant SRH-mortality associations were exclusive to men and those with at least primary education. The adjustment of "regular physical activity", "leisure activity", "activities of daily living (ADL)", and "cognitive function" all led to noticeable attenuation to the SRH-mortality association, with "leisure activity" causing the most attenuation (64.9%) in the "Good SRH" group. Conclusions: Self-rated health is significantly associated with all-cause mortality among the oldest old population in China, particularly among men and the educated, and is considerably explained by regular physical activity, leisure activity, ADL, and cognitive function. We advocate the use of SRH as a simple and efficient tool in research and (potentially) health care practices.