The association of disparities in neighborhood median household income and mortality in patients admitted to the hospital with atrial fibrillation

Background: Lower neighborhood median household income (nMHI) is associated with increased adverse outcomes in patients with atrial fibrillation (AF). However, its effect on mortality is yet unknown.

Methods: Data from the regional United States (U.S.) electronic medical records database, Research Action for Health Network (REACHnet), was extracted for adult patients with AF at Tulane Medical Center over 10 years. Annual nMHI & neighborhood high school graduation (HSG) data was collected from the US Census bureau. Only African Americans (AA) and Caucasians (CC) who had socioeconomic data were included. Low nMHI and low HSG were defined as ≤$25,000 & <90% respectively. High nMHI and HSG were defined as >$50,000 & ≥90% respectively. Primary endpoints were all cause and cardiovascular (CV) mortality. Cox-proportional hazard ratios were used to evaluate the endpoints.

Results: We included 4616 patients diagnosed with AF. During a median follow up of 4.6 years, 434 patients died of which 32.7% patients had CV mortality. There was a stepwise decrease in incidence of both all-cause and CV mortality as nMHI increased. Patients with low nMHI had the greatest risk of all-cause mortality (HR 1.9, C.I. 1.2-3.2, P 0.004). The association between low nMHI and all-cause mortality persisted after adjusting for age, sex, race, HSG and stroke risk factors using CHA₂DS₂VASC, delta CHA₂DS₂VASC scores and oral anticoagulant use. CV mortality followed a similar trend as all-cause mortality, however, this association was not significant after adjusting for the above variables. Apart from low nMHI, CHA₂DS₂VASC delta CHA₂DS₂VASC were statistically significant independent predictors of both all-cause and CV mortality.

Conclusion: Low nMHI is an independent risk factor for all cause and CV mortality in AF. Higher burden of co-morbidities is the driving force behind this disparity. Future studies should evaluate the role of educational and therapeutic intervention in these populations to reduce mortality.