Abstract P271: Sedentary Behavior and Subclinical Atherosclerosis in African Americans: The Jackson Heart Study
Background: Previous studies have reported no association between sedentary time and cardiovascular disease (CVD) risk among African Americans. These findings, however, were limited by lack of assessment of sedentary behavior in both leisure and non-leisure settings. To elucidate this relation, we investigated the association between leisure and non-leisure sedentary behaviors and carotid intima-media thickness (CIMT), a subclinical atherosclerosis measure, in a community-based sample of African Americans. Methods: We studied 5,301 participants from the Jackson Heart Study, a single-site, community-based study of African Americans residing in Jackson, MS. CIMT was assessed by ultrasonography and represented mean far-wall thickness across the right and left side of the common carotid artery. Sedentary behaviors (television [TV] viewing time and occupational sitting) were assessed by an interviewer-administered questionnaire. Analyses for TV viewing were restricted to participants with complete data on CIMT and TV viewing (n=5001). Analyses for occupational sitting were restricted to employed participants with complete data on CIMT and occupational sitting (n=3436). Results: For TV viewing, 28%, 34%, and 38% of participants watched TV <2 hrs/day, 2-4 hrs/day, and >4 hrs/day, respectively. For occupational sitting, 28%, 29%, and 43% of participants reported sitting at work ‘never or seldom’, ‘sometimes’, and ‘often or always’, respectively. In a multivariable analysis of covariance model that included physical activity, longer TV viewing time was associated with greater CIMT (adjusted mean ± SE, <2 hrs/day: 0.72 ± 0.01 mm, 2-4 hrs/day: 0.73 ± 0.01 mm, >4 hrs/day: 0.74 ± 0.01 mm; P-trend <0.001). In employed participants, occupational sitting was associated with lower CIMT (adjusted mean ± SE, ‘never or seldom’: 0.73 ± 0.01 mm, ‘sometimes’: 0.70 ± 0.01 mm, ‘often or always’: 0.71 ± 0.01 mm; P-trend=0.032). In a log-binomial regression model, adjusted prevalence ratios (95% CI) for being in the highest quartile of CIMT for participants who watched TV 2-4 hrs/day and >4 hrs/day vs. those who watched TV <2 hrs/day (referent) were 1.07 (0.94-1.23) and 1.27 (1.12-1.45), respectively (P-trend <0.001). The adjusted prevalence ratios of being in the highest quartile of CIMT for occupational sitting ‘sometimes’ and ‘often or always’ vs. ‘never or seldom’ (referent) were 0.80 (0.68-0.94) and 0.85 (0.73-0.98), respectively (P-trend=0.015). Conclusions: Longer TV viewing time was associated with greater CIMT, while occupational sitting time was associated with lower CIMT. These findings suggest the role of sedentary behaviors in the pathogenesis of CVD among African Americans may vary by leisure and occupational domains. Future studies in African Americans should consider assessing multiple domains of sedentary behavior when evaluating the sedentary behavior-CVD risk association.
Author Disclosures: K.M. Diaz: None. J.N. Booth: None. S.R. Seals: None. S.P. Hooker: None. P.M. Dubbert: None. P. Muntner: B. Research Grant; Significant; Amgen Inc.. D. Shimbo: None.
- © 2015 by American Heart Association, Inc.