Socioeconomic disadvantages over the life-course and their influence on obesity among older Hong Kong Chinese adults

Background: The life-course perspective on socioeconomic inequality in health is a burgeoning field of research. Nonetheless, the three classic life-course models (i.e. sensitive period, cumulative risk and social mobility models) have rarely been simultaneously applied to studies on obesity. Therefore, this study examined the associations of socioeconomic positions (SEPs) across life stages and their associated life-course models with both general and abdominal obesity. Methods: Face-to-face interviews were conducted among 1077 community-dwelling adults aged 50 or above during 2014-15 in Hong Kong. Experiences of poverty, educational attainment and deprivation of necessities represented respondents' SEP in childhood, early adulthood and late adulthood, respectively. General and abdominal obesity were defined as body mass index >= 25 kgm(-2) and waist-to-height ratio >0.5. Multivariable modified Poisson regression with a robust error variance was performed. Results: Respondents with low childhood SEP tended to have reduced risk of general obesity [relative risk (RR) = 0.85; 95% confidence interval (CI) = 0.72-1.00], whereas those with low childhood SEP and low late-adulthood SEP tended to have increased risk of abdominal obesity (RR = 1.10; 95% CI = 1.00-1.21 and RR = 1.14; 95% CI = 1.03-1.26, respectively). Cumulative socioeconomic disadvantages showed a dose-response relationship with abdominal obesity. Also, those with upward socioeconomic mobility had lower risk of abdominal obesity, whereas those with downward socioeconomic mobility had greater risk. Conclusions: Low SEP, especially in childhood, exerted contrasting effects on general and abdominal obesity among older Hong Kong Chinese adults. The three life-course models operated simultaneously in determining the risk of abdominal obesity, while support for cumulative risk and social mobility models was weak in general obesity.