Abstract MP96: High Sedentary Activity Mediates the Association of Acculturation and Obesity in Mexican-American Adults: the National Health and Nutrition Examination Survey (NHANES) 2007-2010
Authors: Murillo Rosenda , Albrecht Sandra S , Daviglus Martha L , Kershaw Kiarri N 
Published: July 2021

Background:
Higher levels of acculturation are associated with both higher leisure-time physical activity (LTPA), and higher obesity rates. However, few studies have examined associations of acculturation with other types of activity. Moreover, the extent to which these activities mediate relationships between acculturation and obesity is unknown. We examined associations of acculturation with four types of activity (moderate-vigorous LTPA, moderate-vigorous work- and transportation-related physical activity, and sedentary activity), and we tested whether these types of activity mediate the acculturation-obesity association among Mexican-American (MA) adults.

Methods:
We used cross-sectional data from 1,982 NHANES 2007-2010 MA participants aged 20+ years. Multinomial logistic regression (MLR) models were used to estimate associations of acculturation (based on nativity and length of residence in the US) with type of activity. Structural equation modeling was used to quantify the extent to which the four types of activity mediate the association of acculturation with obesity (BMI≥30 kg/m
2
).

Results:
Foreign-born (FB) MAs had lower mean minutes per week of LTPA and sedentary activity but higher mean minutes of work and transportation activity, compared to US-born MAs. After adjusting for age, age
2
, gender, education and employment status in the MLR analyses, FB MAs living in the US < 10 years were significantly less likely to perform recommended levels of LTPA (≥150 minutes/week) (Relative Risk Ratio (RRR): 0.67; 95% Confidence Interval (CI): 0.49, 0.92), but they were less likely to be sedentary (RRR: 0.15; 95% CI: 0.08, 0.26) and more likely to engage in high transportation- (RRR: 1.57; 95% CI: 1.12, 2.22) and work-related activities (RRR: 1.57; 95% CI: 1.02, 2.40) than US-born MAs. Adjusted MLR analyses also showed that FB MAs living in the US ≥ 10 years were more likely to perform high transportation activity (RRR: 1.37; 95% CI: 1.04, 1.81) and less likely to engage in high sedentary activity (RRR: 0.27; 95% CI: 0.22, 0.35) than US-born MAs. FB MAs living in the US < 10 years and ≥ 10 years were both less likely to be obese compared to US-born MAs in sociodemographic-adjusted models. Sedentary activity was the strongest mediator of the acculturation-obesity association, accounting for 19.2% and 31.3% of the total effect of acculturation on obesity among FB MAs living in the US <10 years and ≥10 years, respectively, compared to US-born MAs. The direct effect of acculturation on obesity (i.e., independent of all measured mediators and confounders) remained significant for both FB MAs living in the US <10 years and those living in the US ≥10 years, compared with US-born MAs.

Conclusions:
These findings suggest higher sedentary activity may account for a substantial portion of the negative impact of acculturation on obesity. However, the mediation results suggest other factors also play a role.