A comparison of perceived uselessness between centenarians and non-centenarians in China.

BACKGROUND: Self-perceived uselessness is associated with poorer health in older adults. However, it is unclear whether there is a difference in self-perceived uselessness between centenarians and non-centenarians, and if so, which factors contributed to the difference.

METHODS: We used four waves of a nationwide longitudinal dataset from 2005 to 2014 in China to investigate these research goals. We first performed multinomial logit regression models to examine the risk of the high or moderate frequency of self-perceived uselessness relative to the low frequency among centenarians (5778 persons) in comparison with non-centenarians aged 65-99 (20,846 persons). We then conducted a cohort analysis for those born in 1906-1913, examining differences in self-perceived uselessness between those centenarians and those died between ages 91 and 99 during 2005-2014.

RESULTS: Compared to persons aged 65-79, centenarians had 84% (relative risk ratio (RRR) = 1.84, 95% CI:1.69-2.01) and 35% (RRR = 1.35, 95% CI: 1.25-1.46) higher risk to have the high frequency and the moderate frequency of feeling useless versus low frequency, respectively, when only demographic factors were controlled for. However, centenarians had 31% (RRR = 0.69, 95% CI: 0.54-0.88), 43% (RRR = 0.57, 95% CI: 0.49-0.68), and 25% (RRR = 0.75, 95% CI: 0.67-0.83) lower risk, respectively, to have the high frequency of self-perceived uselessness relative to the low frequency when a wide set of study covariates were controlled for. In the case of the moderate versus the low frequency of self-perceived uselessness, the corresponding figures were 18% (RRR = 0.82, 95% CI: 0.66-1.02), 22% (RRR = 0.78, 95%CI: 0.67-0.90), and 13% (RRR = 0.87, 95% CI: 0.79-0.96), respectively. The cohort analysis further indicates that those who became centenarians were 36-39% less likely than those died at ages 91-94 to report the high and the moderate frequencies of self-perceived uselessness versus the low frequency; no difference was found between centenarians and those died at ages 95-99. In both period and cohort analyses, behavioral and health-related factors affected the perception substantially.

CONCLUSIONS: Overall, centenarians were less likely to perceive themselves as useless compared to non-centenarians of younger birth cohorts when a wide set of covariates were considered and non-centenarians of the same birth cohort. How centenarians manage to do so remains an open question. Our findings may help improve our understanding about the longevity secrets of centenarians.