“Association between Median Household Income, State Medicaid Expansion Status, and COVID-19 Outcomes Across US Counties”

Abstract

Objective: The relationship between socioeconomic status and its interaction with State Medicaid-expansion policies on COVID-19 outcomes across United States (US) counties are uncertain. To determine the association between median-household-income and its interaction with State Medicaid-expansion status on COVID-19 incidence and mortality in US counties Methods: Longitudinal, retrospective analysis of 3142 US counties (including District of Columbia) to study the relationship between County-level median-household-income (defined by US Census Bureau Small-Area-Income-and-Poverty-Estimates) and COVID-19 incidence and mortality per 100000 of the population in US counties from January 20, 2020 through December 6, 2020. County median-household-income was log-transformed and stratified by quartiles. Medicaid-expansion status was defined by US State Medicaid-expansion adoption as of first reported US COVID-19 infection, January 20, 2020. Multilevel mixed-effects generalized-linear-model with negative binomial distribution and log link function compared quartiles of median-household-income and COVID-19 incidence and mortality, reported as incidence-risk-ratio (IRR) and mortality-risk-ratio (MRR), respectively. Models adjusted for county socio-demographic and comorbidity conditions, population density, and hospitals, with a random intercept for states. Multiplicative interaction tested for Medicaid-expansion*income quartiles on COVID-19 incidence and mortality. Results: There was no significant difference in COVID-19 incidence across counties by income quartiles or by Medicaid expansion status. Conversely, significant differences exist between COVID-19 mortality by income quartiles and by Medicaid expansion status. The association between income quartiles and COVID-19 mortality was significant only in counties from non-Medicaid-expansion states but not significant in counties from Medicaid-expansion states (P<0.01 for interaction). For non-Medicaid-expansion states, counties in the lowest income quartile had a 41% increase in COVID-19 mortality compared to counties in the highest income quartile (MRR 1.41, 95% CI: 1.25-1.59). Conclusions and Relevance: Median-household-income was not related to COVID-19 incidence but negatively related to COVID-19 mortality in US counties of states without Medicaid-expansion. It was unrelated to COVID-19 mortality in counties of states that adopted Medicaid-expansion. These findings suggest that expanded healthcare coverage should be investigated further to attenuate the excessive COVID-19 mortality risk associated with low-income communities.

The effect of obesity-related traits on COVID-19 severe respiratory symptoms is mediated by socioeconomic status: a multivariable Mendelian randomization study

“…Previously, a longitudinal study reported a negative relationship between HI and COVID-19 mortality, which might be considered an extreme COVID-19 phenotype [45]. Interestingly, there was no difference in COVID-19 infection rate among the different income groups [45]. Hence, these previous results and ours suggest that HI influences only COVID-19 severe phenotypes.…”

“…The mechanisms by which HI is mediating the association between obesity-related anthropometric traits and COVID-19 might be similar to those proposed for other known health outcomes. In general, low-income populations have reduced access to medical care, with subsequent worse health at baseline and lower opportunity to receive adequate treatment to health complications in comparison with high-income groups [45,46]. Finally, these healthcare inequalities are translated into a higher morbidity and mortality risk in communities with a lower household income [47].…”

“…In our study, we found that genetically determined HI had a negative causal effect on both very severe respiratory confirmed COVID-19 and hospitalized COVID-19. Previously, a longitudinal study reported a negative relationship between HI and COVID-19 mortality, which might be considered an extreme COVID-19 phenotype [45]. Interestingly, there was no difference in COVID-19 infection rate among the different income groups [45].…”

“…Although these public policies will not modify the genetic factors involved in the development of severe COVID-19 symptoms, they might impact modifiable risk factors and reduce social inequalities. For example, strategies that improve the access to adequate medical services might lead to the adverse impact of COVID-19 in low-income communities [45].…”

The association of obesity-related traits on COVID-19 severity and hospitalization is affected by socio-economic status: a multivariable Mendelian randomization study

“…In general, low-income populations have reduced access to medical care, with subsequent worse health at baseline and lower opportunity to receive adequate treatment to health complications in comparison with high-income groups. 52 , 53 Finally, these healthcare inequalities are translated into a higher morbidity and mortality risk in communities with a lower household income. 54 …”