Life-course social disparities in body mass index trajectories across adulthood: cohort study evidence from China Health and Nutrition Survey
Curation statements for this article:-
Curated by eLife
eLife assessment
This work shows that higher socioeconomic status is associated with a higher risk of obesity, which should inform China's obesity public health programs and policies, and also be of interest to other countries and communities. The evidence supporting the conclusions is strong, but the data analysis is incomplete and would benefit from more rigorous approaches.
This article has been Reviewed by the following groups
Listed in
- Evaluated articles (eLife)
- Scientific Communication and Education (eLife)
Abstract
Background
The social disparities in obesity may originate in early life and adult social class. There are various developmental trajectories of overweight/obesity in adulthood. It is unclear how the intergenerational mobility of socioeconomic status influences adult overweight/obesity in China.
Methods
We used longitudinal data from ten waves of the China Health and Nutrition Survey (CHNS) between 1989 and 2015 for our analysis. The group-based trajectory modeling was used to identify BMI trajectories in adulthood. Multinomial logistic regression was adopted to assess the associations between SES and adult BMI trajectories.
Results
Among a total of 3,138 participants, three latent clusters, including normal-stable BMI (51.4%), progressive overweight group (39.8%), and progressive obesity group (8.8%), were identified. High father’s occupational position, high participants’ occupation position and educational attainment, respectively, were associated with greater obesity risk. Compared to a stable low life course SES trajectory, a stable high life course SES trajectory was associated with a 2.35-fold risk of obesity, and upward and downward social mobility trajectories increased the risk for overweight/obesity. Individuals in the highest relative to the lowest life course cumulative socioeconomic score group had around twice risk of obesity.
Conclusions
The results emphasize the role of the high SES in early life and life-course SES accumulation, in the obesity intervention in China.
Funding
All the work was supported by the National Natural Science Foundation of China (Grant Nos. 72174167, 81602928) and Natural Science Foundation of Shaanxi (2021JM-031).
Article activity feed
-
eLife assessment
This work shows that higher socioeconomic status is associated with a higher risk of obesity, which should inform China's obesity public health programs and policies, and also be of interest to other countries and communities. The evidence supporting the conclusions is strong, but the data analysis is incomplete and would benefit from more rigorous approaches.
-
Reviewer #1 (Public Review):
Overall, the paper by Dang and colleagues is an interesting addition to the field. This study investigates the relationship between socioeconomic status and lifetime obesity using group-based trajectory modeling. The authors identified three trajectories overall, the most prevalent being stable normal BMI. Overall, higher SES was associated with a greater risk of obesity, which is contradictory to studies that examine the relationship among developed countries. Their findings and conclusions are supported by their analysis/data, however, some consideration and additional details are needed to help understand and be more confident in the final results.
Strengths of this study include:
- The use of novel techniques to investigate the relationship between SES and lifetime obesity, which is important for …
Reviewer #1 (Public Review):
Overall, the paper by Dang and colleagues is an interesting addition to the field. This study investigates the relationship between socioeconomic status and lifetime obesity using group-based trajectory modeling. The authors identified three trajectories overall, the most prevalent being stable normal BMI. Overall, higher SES was associated with a greater risk of obesity, which is contradictory to studies that examine the relationship among developed countries. Their findings and conclusions are supported by their analysis/data, however, some consideration and additional details are needed to help understand and be more confident in the final results.
Strengths of this study include:
- The use of novel techniques to investigate the relationship between SES and lifetime obesity, which is important for understanding the life course of disease and for designing future public health interventions and strategies.
- A large sample size.
- The use of a population-based sampling strategy to recruit participants, which helps the generalizability of findings and limits volunteer bias.
- The availability of data on SES and height/weight over a 20-year follow-up, including objectively measured weight and height.
- The availability of important confounders (e.g., physical activity, energy intake).While overall it is an interesting study, there are some considerations and unclarities that should be addressed.
Weaknesses of this study include:
- Lack of clarity on how the authors conceptualize and define socioeconomic status in some sections of the paper. A limitation is the definition of SES only encompasses educational attainment and occupation, and not other aspects (e.g. income, social class). However, most studies published to date also focus mostly on education and occupation.
- A large majority (~90%) of participants were excluded from the analysis due to missing data on exposures and outcomes. This is a substantial proportion, and it is quite possible that this may have resulted in selection bias for those included vs. those not included, and may limit the generalizability of the findings.
- As with all studies that use self-reported data, there is some potential for information bias. However, the authors do acknowledge this as a limitation in their study.
- There is a lack of clarity with some of the methods (e.g. how multinomial logistic regression was used, latent classes, and how confounders were chosen). The paper would benefit from the inclusion of these details. -
Reviewer #2 (Public Review):
The authors aimed to explore the relationship between life course SES and BMI trajectories. They achieve the aim partially, and they could present the results more clearly. The work is interesting and will inform China's obesity public health programs and policies, but it is also interesting for other countries and communities. The exploration of life course exposures is relevant in many ways, and the authors did a good job conceptualizing the BMI and SES trajectories. However, some issues need to be improved, such as the discussions about bias and improvements in the writing and presentation of results.
-
