Study Depicts Strong Associations Between Social Factors and Mortality Risk Following Coronary Artery Bypass Grafting A Population-Based Cohort Study

According to an observational study posted in the Journal of American Heart Association, there were strong associations between social factors and mortality risk after CABG in both men and women. These results emphasized the importance of developing and implementing secondary prevention strategies for socially disadvantaged CABG patients.

Prior to this study, little was known of the impact of social factors on mortality after coronary artery bypass grafting (CABG). Therefore, Susanne Nielsen and her colleagues explored sex- and age-specific associations between mortality risk after CABG and marital status, income, and education. This population-based register study included a total of 110,742 CABG patients (21.3% women) from the SWEDEHEART registry (Swedish Web-system for Enhancement and Development of Evidence-based Care in Heart Disease Evaluated According to Recommended Therapies) operating between 1992 to 2015. As this was a time-to-event analysis, a Cox regression model was used to study the relationship between social factors and all-cause mortality. Interestingly, the authors found that never having been married compared with being married/cohabiting was associated with a higher risk in women than in men (hazard ratio 1.32, 95% CI 1.20–1.44) versus 1.17 (1.13–1.22), P=0.030 between sex. Moreover, the lowest income quintile, compared with the highest, was associated with higher risk in men than in women (hazard ratio 1.44 [1.38–1.51] versus 1.25 [1.14–1.38], P=0.0036). Additionally, the lowest education level was associated with a higher risk without sex difference (hazard ratio 1.15 [1.11–1.19] versus 1.25 [1.16–1.35], P=0.75). Not surprisingly, for unmarried women aged 60 years at surgery with low income and low education, mortality 10 years after surgery was 18%, compared with 11% in married women with high income and higher education level. The median life expectancy was 4.8 years shorter. The corresponding figures for 60-year-old men were 21% versus 12% mortality risk at 10 years and 5.0 years shorter life expectancy.

The investigators drew the conclusion that social factors such as low education, not being married, and low household income was associated with increased mortality risk after coronary artery bypass grafting in both men and women. They estimated that disadvantages in social risk factors shortened median life expectancy after coronary artery bypass grafting by 4 to 5 years for both men and women. Therefore, the results emphasized the importance of developing better educational approaches for secondary prevention strategies, particularly in coronary artery bypass grafting patients with severe social disadvantages. Susanne Nielsen and her colleagues believed that this meant that healthcare professionals needed to support and increase patients’ knowledge about secondary prevention strategies after coronary artery bypass grafting.

Despite these interpretations, the present study shared the limitations of any population-based registry study, including bias from unregistered variables such as smoking, obesity, diet, physical activity, stress, the extent of the coronary artery disease, cardiac function, and selection bias. Although several factors were adjusted for, information about these clinical and lifestyle factors may have influenced the results. Income was measured as household income, and it was possible that this measure was not representative of each individual’s economic capacity; some individuals could have had a low income because of illness and inability to work but could probably be supported by income from their spouses. The main strength of this study, however, was that it included a large nationwide sample, data collection from different registries and databases, and an extensive follow-up period (24 years). This large sample size allowed the analysis of smaller subgroups, such as younger men and women. Taking these findings into perspective and speaking of the scope of future research in this field, investigator Martin Karlsson stated, “Individuals with a stressful economic situation have fewer opportunities to follow advice about a healthier lifestyle, and educational level may also influence the chance to adopt a healthy lifestyle. Hence, there is room for improvement in educational approaches to increase patients’ knowledge of the importance of secondary prevention but also to make the adherence to secondary prevention strategies sustainable, particularly to those with the highest burden of social disadvantages. Customized advice in secondary prevention related to patient abilities need to be thoroughly implemented and evaluated regularly. Future research should focus on the impact of how different pedagogical approaches affect patients’ adherence to secondary prevention and whether this leads to reduced mortality, specifically in vulnerable groups undergoing CABG.”