Psychological wellbeing and all-cause mortality in the oldest old in China: a longitudinal survey-based study.

BACKGROUND: Although the relationship between psychological wellbeing and physical health has been the subject of many studies among middle-aged and older adults, little is known about whether psychological wellbeing is associated with mortality among the fastest growing population segment-the oldest old (aged ≥80 years).

METHODS: This study included 18 676 adults aged 80-122 years from the Chinese Longitudinal Healthy Longevity Survey, conducted in 22 of 31 provinces in China in 1998 and followed up in 2000, 2002, 2005, 2008-2009, 2011-12, and 2014. Psychological wellbeing was measured by seven items covering positive (optimism, sense of personal control, conscientiousness, and positive feelings about ageing) and negative (loneliness, anxiety, and loss of self-worth) affects with a five-point Likert scale. A psychological wellbeing index was constructed from the sum of these seven items, and scores were divided by quartile (Q1 0-22, Q2=23-25, Q3 26-28, and Q4 28-35), with higher scores indicating better wellbeing. The association between psychological wellbeing and all-cause mortality was evaluated with multivariable Cox proportional hazards regressions. Duke University Health System's Institutional Review Board, the National Bureau of Statistics of China, and the Ethical Committee of the Social Science Division of Peking University reviewed and approved ethics for the Chinese Longitudinal Healthy Longevity Survey study. Written consent was obtained from all participants or their proxies.

FINDINGS: The mean age of the study population (58·8% women, n=10977) at baseline was 92 years (SD 7·4). Most participants (89·2%, n=16 661) died during follow-up, which ranged from 0·1 to 16·5 years (median 2·8). Compared with participants with a Q1 wellbeing score, hazard ratios for death were 0·95 (0·91 -0·99) for those with a Q2 score, 0·90 (0·86-0·94) for Q3, and 0·84 (0·79 -0·88) for Q4 (all p values <0·0001) after adjustment for potential confounders, including age, sex, co-residence, residence, education, marital status, lifestyle, and self-reported health. Similar patterns were found in stratified analysis among people with and without chronic diseases (hypertension, diabetes, cardiovascular diseases, stroke, and respiratory diseases).

INTERPRETATION: In a large sample of Chinese oldest old, we found a dose-response association between psychological wellbeing and all-cause mortality. Our results, if substantiated by future research, suggest that psychological factors in older age might have a role in longevity.

FUNDING: The China Longitudinal Healthy Longevity Survey from which the data used in this article were derived was jointly funded by the US National Institute on Aging (grant R01 AG023627), China Natural Science Foundation (grants 70533010, 71110107025, 71233001, and 71490732), United Nations Population Fund, China Social Sciences Foundation, and Hong Kong Research Grants Council.