Sex-specific role of education on the associations of socioeconomic status indicators with obesity risk: A population-based study in South Korea

PLOS ONE, Nov 2019

Background No study of obesity risk for people in developed countries has conducted a multi-dimensional analysis of the association of socioeconomic status with obesity. In this paper, we investigated if education functions as either a confounder or an effect modifier in the association of another socioeconomic status indicator with obesity. Methods This cross-sectional study analyzed data of an adult population sample (10,905 men and 14,580 women) from the Korea National Health and Nutrition Examination Survey (2010–2014). The study performed multivariate logistic regression analyses for three education levels and four indicators of socioeconomic status (i.e., marital status, residential area, occupation, and income). Results The overall prevalence of obesity was 38.1% in men and 29.1% in women (p < 0.001). In men, while education functioned as an effect modifier in the association between marital status and obesity (p for interaction = 0.006), it functioned as both a confounder (p < 0.001) and an effect modifier (p for interaction < 0.001) in the association between residential area and obesity. In contrast, in women, education functioned as a confounder in the association of residential area with obesity (p = 0.010). However, it functioned as both a confounder (p < 0.001) and an effect modifier (p for interaction = 0.012) in the association between income and obesity. A prediction showed that unlike in women, education was positively associated with obesity risk for some socioeconomic indicator groups in men; for example, in a rural resident group, a higher level of education increased the probability of being obese by 19.7%. Conclusions The present study suggests the need to examine sex-specific studies regarding the role of education on the association between other socioeconomic status indicators and obesity. This should be considered in planning education policies to reduce the risk of obesity.

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Sex-specific role of education on the associations of socioeconomic status indicators with obesity risk: A population-based study in South Korea

January Sex-specific role of education on the associations of socioeconomic status indicators with obesity risk: A population- based study in South Korea Woojin Chung 0 1 Jaeyeun Kim 0 Seung-ji Lim 0 Sunmi Lee 0 0 Editor: Meian He, Tongji Med College , HUST , CHINA 1 Department of Health Policy, Graduate School of Public Health, Yonsei University , Seoul , Republic of Korea, 2 Institute of Health Services Research, Yonsei University , Seoul , Republic of Korea, 3 Department of Public Health, Graduate School, Yonsei University , Seoul , Republic of Korea, 4 Health Insurance Policy Research Institute, National Health Insurance Service , Wonju-si , Republic of Korea - OPEN ACCESS Data Availability Statement: Data are from the Fifth and Sixth Korea National Health and Nutrition Examination Survey, which is available from the Korea Centers for Disease Control and Prevention database (https://knhanes.cdc.go.kr/knhanes/main. do). These are third party data and free of charge to anyone. Interested researchers can download the data through a simple registration process. Funding: The authors received no specific funding for this work. Background Methods Results Competing interests: The authors have declared that no competing interests exist. Conclusions The present study suggests the need to examine sex-specific studies regarding the role of education on the association between other socioeconomic status indicators and obesity. This should be considered in planning education policies to reduce the risk of obesity. Introduction Worldwide, obesity has become an important public health problem. Obesity can cause various diseases and a diminished quality of life for individuals [ 1 ], and it can cause a heavy economic burden by increasing a society's medical expenditures, decreasing manpower, and thereby reducing labor productivity [ 2,3 ]. Regardless of whether they were for academic curiosity or policy development, numerous studies have examined factors associated with obesity risk. Among these factors, the association between socioeconomic status and obesity risk has attracted much attention across many disciplines. Generally, the consensus has been that in developed countries, a higher socioeconomic status is associated with a lower risk of obesity in both men and women [4±6]. Meanwhile, recent studies from developed countries point to a more complex association between socioeconomic status indicators and obesity risk, thereby asking for more and better research on the association. For example, studies from Canada [ 7 ], France [ 8 ], Luxembourg [ 9 ], the United States [ 10 ], and South Korea [ 11 ] suggest that the association between a particular socioeconomic status indicator and obesity risk may not only be positive in one sex, but negative in the other sex. Unfortunately, despite a lot of attention paid to the associations between socioeconomic status indicators and obesity risk, a study of a multi-dimensional analysis on the associations has not been performed for people in developed countries. This lack of studies may lead to the unavailability of adequate information for developing theories and designing efficient public health policies aimed at reducing obesity risk in specific groups of people. Therefore, the aim of the present study was to employ a multi-dimensional analysis and examine the role of education on the association between other socioeconomic status indicators (such as marital status, residential area, occupation, and income) and obesity. In the present study, we elected to focus on the role of education among the various socioeconomic status indicators because education level is established during early adulthood and generally remains unchanged unlike the other socioeconomic indicators that are more susceptible to change. In this study, we sought to identify education as either a confounder or an effect modifier or both a confounder and effect modifier in the association between another socioeconomic status indicator and obesity. In addition, after considering the role of education in the association between another socioeconomic status indicator and obesity, the study aimed to investigate if a higher level of education was associated with a reduced risk of obesity in both men and women. To fulfill the aims of the study, we analyzed a sample adult population aged 25 years from the nationally representative data in South Korea; this population was selected because the country is one of the largest developed countries in the world [ 12 ], and people in this age group were thought to have most likely completed their education. Materials and methods Data source and study sample We used data from the Fifth and Sixth Korea National Health and Nutrition Examination Survey (KNHANES V and VI, 2010±2014), performed by the Korea Centers for Disease Control 2 / 16 and Prevention. The sampling design for the KNHANES was a stratified, multistage probability survey of the (...truncated)


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Woojin Chung, Jaeyeun Kim, Seung-ji Lim, Sunmi Lee. Sex-specific role of education on the associations of socioeconomic status indicators with obesity risk: A population-based study in South Korea, PLOS ONE, 2018, Volume 13, Issue 1, DOI: 10.1371/journal.pone.0190499