Introduction: Both individual-level socioeconomic position (SEP) and the socioeconomic context of neighborhood of residence are important social determinants of cardiovascular health. However, few studies have considered how both individual and neighborhood socioeconomic factors simultaneously impact the effect of an intervention on cardiovascular health.
Hypothesis: We assessed the hypothesis that higher individual SEP and lower neighborhood poverty and would each be independently associated with better cardiovascular health in response to the Examination of Mechanisms (E-Mechanic) of Exercise-Induced Weight Compensation randomized control trial.
Methods: Cardiovascular health (CVH) was measured via a composite score that included 4 factors (1) BMI, 2) cholesterol, 3) glucose, and 4) systolic blood pressure), each categorized as ideal (2 points), intermediate (1 point), and poor (0 points) health for a possible range of 0 points (worst CVH) to 8 points (best CVH). CVH scores were calculated at baseline and follow-up. Individual SEP was created using principal components analysis with income and educational attainment, controlling for race, to produce a single socioeconomic factor that was dichotomized to indicate high (=1) or low (=0) SEP. Neighborhood socioeconomic context was measured at the census block group using percent (%) poverty derived from the U.S. Census Bureau’s American Community Survey. We estimated a multilevel repeated-measures regression model of CVH against individual SEP and neighborhood poverty that included covariates for age, sex, race, and marital status.
Results: The final analytic sample included 114 participants (mean age = 48.3 years, SD age = 11.5 years; 72% female; 30% African American; 72% married) residing in 88 neighborhoods (mean poverty = 14.5%, SD=13.3%) who received the E-Mechanic exercise intervention and who had no missing data for all variables. On average, the E-Mechanic trial improved cardiovascular health among all exercise intervention participants by 0.3 points (95% CI 0.2 to 0.5). Results from the regression model demonstrated that participant SEP only approached marginal significance (p=0.12), while neighborhood poverty was not significant (p=0.32).
Conclusions: The current study found that individual and neighborhood socioeconomic characteristics were not independently associated with response in cardiovascular health to the E-Mechanic exercise intervention. While findings from the analysis do not implicate either personal or contextual socioeconomic influences in intervention response for the E-Mechanic trial, this study does address the need to assess potential disparities in randomized control trials by examining differential response in health outcomes among participants by multiple social determinants of health.