Abstract P031: Mediation Effect of Abdominal Adiposity Between Sedentary Lifestyle and Blood Pressure in General Population From a Middle-income Country

Abstract

Background: Hypertension is a highly prevalent risk factor for cardiovascular disease (CVD). Middle-income countries have experienced accelerated urbanization resulting in a growing prevalence of sedentary lifestyle (SL) behavior and a trend toward obesity that might explain population-level changes in blood pressure (BP). We aimed to evaluate the association of SL and adiposity on BP. Methods: We analyzed data from two surveys conducted on representative samples (15-64 years old) from Santander (Colombia) in 2010 (n=2,419) and 2015 (n=2,158) following the WHO STEPwise approach to assess risk factors for CVD. Physical activity was measured using the GPAQ questionnaire and SL was defined as the lowest level of activity according to the WHO criteria. We measured waist circumference (WC [cm]) and calculated body mass index (BMI [kg/m 2 ]) and waist-to-hip ratio (WHR) as indexes of adiposity. BP was measured using an Omron® automatic monitor in sitting position (average of two measurements). Associations were estimated, incorporating post-stratification weights, using censored normal multiple regression (accounting for antihypertensive therapy) and mediation approached by Baron’s criteria. Results: Mean systolic/diastolic (S/DBP) were 119.2 (95%CI: 118.7-119.7) / 73.7 (95%CI: 73.4-74.1) mmHg and 1 out 6 participants were hypertensive (2015/2010 prevalence ratio=1.02, p>0.050). BMI, WC and WHR were positively and significantly correlated with systolic (r=0.16, r=0.39, and r=0.41) and diastolic BP (r=0.18, r=0.38, and r=0.33). Sedentary as compare to active participants had higher age- and sex-adjusted WC (1.1 cm, p=0.008) and WHR (0.01 units, p<0.001). SL prevalence was 62.0% (95%CI: 59.8-64.1) and changed across tertiles of SBP (66.4%, 60.3%, and 59.6%) and DBP (59.3%, 63.1%, and 63.1%); however, SL was only associated to higher DBP after adjustment by age, sex, and area of residency (0.8 mmHg, p=0.036). Further inclusion of BMI, WC, or WHR attenuated the strength of the association in 16.7%, 42.3%, and 61.7%, respectively. There was no survey-by-sedentary lifestyle interaction. Conclusion: SL is highly prevalent in a middle income country such as Colombia. We confirmed the association of this behavioral risk factor and DBP but not SBP. Furthermore, the attenuation of such relationship by anthropometric indexes, particularly of abdominal obesity, suggests a mediation effect of adiposity that must be validated in longitudinal studies.