Socioeconomic Position and Disparities in Cardiovascular Health Response Following the E‐Mechanic Exercise Intervention

Objective We assessed if socioeconomic position (SEP) was associated with response in cardiovascular health to a structured exercise intervention. We further explored potential mechanisms – compensation and energy intake – in the relationship between SEP and disparate response in cardiovascular health. Methods We used data from the Examination of Mechanisms (E‐Mechanic) of Exercise‐Induced Weight Compensation study. Cardiovascular health was measured using 4 health factors, 1) BMI, 2) cholesterol, 3) glucose, and 4) systolic blood pressure, to create a composite cardiovascular health score based upon ideal (2 points), intermediate (1 point), and poor (0 points) health for each factor for a possible range of 0 points (worst CVH) to 8 points (best CVH). These scores were calculated pre‐ and post‐intervention. The primary covariate of interest, socioeconomic position (SEP), was created using principal components analysis with baseline income and educational attainment and partially controlling for race to produce a single factor score that was dichotomized above and below 0 to indicate high (=1) versus low (=0) SEP. Compensation was measured as observed weight loss minus expected weight loss over the course of the intervention. Energy intake (kcals) was measured with laboratory‐based food intake tests administered pre‐ and post‐intervention. Cardiovascular health scores were regressed first against SEP in a linear repeated‐measures regression model, controlling for age, sex, race, and marital status. We next explored potential mediation effects by adding compensation and energy intake (kcals) to the model. Results Among the 106 participants (21–65 years old; 73% female; 30% black; 62% married) who received the E‐Mechanic exercise intervention, the mean cardiovascular health score pre‐ intervention was 5.1 points (SD=1.2 points) and post‐intervention 5.4 (SD=1.2 points). Regression analysis revealed that the exercise intervention increased cardiovascular health overall (p<0.001). However, participants with high SEP had significantly (p=0.007) greater improvement in cardiovascular health. At baseline participants with high SEP had better cardiovascular health, but not significantly better (LS‐means difference = 0.49; p=0.2). Yet, after the intervention the difference in cardiovascular health between high and low SEP participants had increased (LS‐means difference = 0.78 (p=0.01). To test the potential mediating effect of compensation and energy intake for SEP disparities in cardiovascular health, we next included both measures in the regression analysis. Results showed that the association between SEP disparities in cardiovascular health response did not change substantially after adjusting for compensation and energy intake. Conclusions Response in cardiovascular health to the E‐Mechanic exercise intervention was influenced by socioeconomic position. Although cardiovascular health improved on average for intervention participants, those with higher socioeconomic position demonstrated better improvement in cardiovascular health factor scores, thus increasing socioeconomic health disparities. However, potential mechanisms ‐ energy intake and compensation ‐ did not explain this disparity. Support or Funding Information This research was supported by F32HL123242 and R01HL102166 from the National Heart Lung and Blood Institute, 1 U54 GM104940 from the National Institute of General Medical Sciences, which funds the Louisiana Clinical and Translational Science Center (LA CaTS), and NORC Center Grant #P30DK072476 entitled “Nutrition and Metabolic Health Through the Lifespan” sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases, all of which are institutes of the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of funding sources. The authors declare that they have no competing interests.