Cognitive impairment and mortality among the oldest-old Chinese

Abstract

Objective: This study examined the relationship between cognitive impairment status and all-cause mortality among the oldest-old Chinese.

Methods: A total of 7474 survey participants 80 years of age and above came from the Chinese Longitudinal Healthy Longevity Survey 1998-2012 waves. Baseline cognitive impairment status was assessed using the Chinese version of the mini-mental state examination (MMSE), with total score ranging from 0 to 30. Cox proportional hazards regressions were performed to examine the relationship between baseline cognitive impairment status in 1998 and subsequent all-cause mortality during 1998-2012, adjusting for various individual characteristics at baseline.

Results: Compared with those with no or mild cognitive impairment (18 ≤ MMSE score ≤ 30) at baseline, participants with moderate-to-severe cognitive impairment (0 ≤ MMSE score ≤ 17) were 28% (95% confidence interval = 20%, 37%) more likely to die during the follow-up period from 1998 to 2012. A dose-response relationship between baseline severity level of cognitive impairment and mortality was evident. Compared with those without cognitive impairment (25 ≤ MMSE score ≤ 30) at baseline, those having mild cognitive impairment (18 ≤ MMSE score ≤ 24), moderate cognitive impairment (10 ≤ MMSE score ≤ 17), and severe cognitive impairment (0 ≤ MMSE score ≤ 9), were 20% (13%, 28%), 38% (27%, 51%), and 47% (33%, 62%) more likely to die during the follow-up period. No statistically significant gender differences in the relationship between cognitive impairment status and mortality were found.

Conclusion: Baseline cognitive impairment was inversely associated with longevity among the oldest-old Chinese. Copyright © 2016 John Wiley & Sons, Ltd.

Keywords: Chinese; cognitive impairment; mortality; oldest-old.