Socioeconomic status and clinical outcome: A microeconomic study

Findings from empirical studies in economics reveal that higher mortality and morbidity (i.e., worse health) are associated with lower socioeconomic status (SES). This association is termed “Social Gradient”. The Social Gradient in health is seen globally and affects underdeveloped, developing and developed economies. In other words, heath inequality occurs everywhere. While there are different measures in the SES and health, our research aims at finding the magnitude of this association at the individual level. We focused on the relationship between income (a proxy for the SES), and a specific clinical outcome cardiovascular disease (CVD). The statistics shows that CVD accounts for almost one-third of all deaths in the world; CVD is also the leading cause of death for both men and women in the United States and accounts for one-fourth of all deaths in the U.S. population. Given the size of CVD incidence and its severity, we examine how it occurs across various levels of the SES. More importantly, finding the relevance of this association may help us better allocate limited resources to places where they are needed.

Median household income data in the U.S. Census Bureau were matched to data for CVD patients from the Myocardial Infarction Data Acquisition System (MIDAS). The longitudinal data was from 2004 to 2015. All patients in this study were 18 years or older. Logit and Cox proportional hazards models were used to study the relationship between income and two clinical outcomes; readmission for acute myocardial infarction (AMI) and cardiovascular-cause (CV-cause) death. Both models were estimated while controlling for other covariates including demographic factors and comorbidities. Our main finding indicates that patients with low income tend to have higher risk for the readmission for AMI. However, the relationship between income and CV-cause death is insignificant.