Importance: Although the association between poor economic or social standing and health is well established, few studies have attempted to examine the mediational pathways that produce adverse outcomes in disadvantaged populations.
Objective: To determine whether barriers to care mediate the association between socioeconomic status (SES) and asthma-related emergency department (ED) visits.
Design, setting, and participants: This cohort study used data from the World Trade Center Health Registry, which comprises rescue and recovery workers and community members who worked, lived, studied or were otherwise present in downtown Manhattan, New York, during or immediately after the September 11, 2001, disaster. Data were matched to an administrative database of ED visits. Those who experienced an asthma-related ED visit and those who did not were compared in bivariate analysis. A mediation analysis was conducted to determine the role of barriers to care in the association between number of ED visits and SES.
Exposures: Education, income, and race/ethnicity, which were collected at first survey in 2003 to 2004.
Main outcomes and measures: Asthma-related ED visits that occurred after survey responses regarding barriers to care were collected (2006-2007) but before 2016, the latest date that data were available.
Results: The analytic sample included 30 452 enrollees (18 585 [61%] male; median [interquartile range] age, 42.0 [35.0-50.0] years; 20 180 [66%] white, 3834 [13%] African American, and 3961 [13%] Hispanic or Latino [any race]). Approximately half (49%) had less than a bachelor's degree, and 15% had an annual income less than $35 000. Those of lower SES were more likely to experience an asthma-related ED visit. Although number of barriers to care mediated this association, they explained only a small percentage of the overall health disparity (ranging from 3.0% [95% CI, 2.3%-3.9%]) of the differences between African American and white individuals to 9.8% [95% CI, 7.7%-11.9%]) comparing those with less than a high school diploma to those with at least a bachelor's degree. However, the association varied by specific barrier to care. Lack of money, insurance, and transportation mediated up to 11.8% (95% CI, 8.1%-15.9%), 12.5% (95% CI, 8.5%-17.4%), and 4.3% (95% CI, 1.7%-8.4%), respectively, of the association between SES and number of ED visits. Lack of childcare, not knowing where to go for care, and inability to find a health care professional mediated a smaller or no percentage of the association.
Conclusions and relevance: The identification of vulnerable subpopulations is an important goal to reduce the burden of asthma-related hospital care. More research is needed to fully understand all of the pathways that lead disaster survivors of lower SES to disproportionately experience ED visits due to asthma.