Trajectory of changes in body roundness index of elderly people in China and its influencing factors: an attribution analysis based on CLHLS cohort

To construct a trajectory model for the changes in body roundness index (BRI) of elderly people in China from 2011 to 2018 based on the data derived from Chinese Longitudinal Healthy Longevity Survey (CLHLS), and analyze the influencing factors of different BRI trajectories.

Based on the longitudinal cohort data from the CLHLS platform, group-based trajectory model (GBTM) analysis was used to construct longitudinal change trajectories of 3 waves of BRI (2011, 2014, and 2018) that meet our research criteria. Unordered multinomial logistic regression analysis was employed to identify the influencing factors of different BRI trajectories.

A total of 2512 valid samples were included in the analysis. The BRI trajectory of Chinese elderly people fitted by GBTM was optimally grouped into low-, medium-, and high-level growth trajectory models. There were statistically significant differences among different BRI trajectory groups in gender, length of education, resident place, living with spouse, retirement pension, sleep quality, smoking history, drinking history, continuous exercise, frequency of fruit consumption, frequency of salt-preserved vegetables consumption, and “fruit+protein” dietary patterns (P<0.05). Disordered multiclass logistic regression analysis found that, using the low-level growth trajectory model as a reference, males and those with a history of smoking were less likely to exhibit moderate to high growth levels of BRI trajectories; Elderly people with retirement pensions were more likely to exhibit a moderate to high growth level of BRI trajectory; People with a history of alcohol consumption were more likely to exhibit a moderate steady growth level of BRI trajectory; People with longer than 10 years of education were less likely to exhibit a high level of growth in the BRI trajectory, while urban residents and those who frequently consumed fruits and salted vegetables were more likely to exhibit a high level of growth in the BRI trajectory.

The trajectory of BRI changes among elderly people in China from 2011 to 2018 can be divided into 3 groups, which are influenced by multiple factors such as gender, resident place, and length of education. It is necessary to pay attention to and make measures in advance to improve the quality of life in the elderly.

It is advisable to incorporate BRI as a core indicator in elderly health monitoring systems, establish a dynamic management mechanism for high-risk populations, and implement precision-targeted lifestyle interventions and health guidance.