The Association between Low-Income Neighborhoods and Post-Traumatic Stress Disorder Diagnoses Among Children on Medicaid: Applying the Income Inequality Hypothesis

Background:  There is growing recognition that addressing traumatic stress requires a focus on risk factors beyond those at the individual-level.  Given that individuals living in poverty and being exposed to violence are risk factors for post-traumatic stress disorder (PTSD), the limited research in this area focuses on low-income communities. Additional research is necessary to determine the degree to which neighborhood conditions contribute to the incidence of PTSD among low-income individuals.  This study seeks to address this gap in the literature by explicating the role of neighborhood income on the incidence of PTSD among children.

Method:This study uses data from the 2015 Nationwide Emergency Department Sample (NEDS) of the Healthcare Cost Utilization Project (HCUP) as distributed by the United States Department of Health and Human Services.  The NEDS contains data on roughly 31 million hospital-based, emergency room visits from 953 hospitals in 34 states and the District of Columbia.  Using Medicaid status as a proxy for low-income status, the data were limited to youth (age <18 years) whose primary or secondary payer was coded as Medicaid. A dichotomous PTSD variable was created (1=yes, 0=no) if any of the first three hospital billing codes were PTSD.  A 10% simple random sample of the non-PTSD group was selected from the larger sample of Medicaid patients without PTSD as a control group due to computational limitations.  The data were stratified by gender and logistic regression was used to predict the incidence of PTSD.  The focal independent variable of neighborhood income was divided into quartiles based on ZIP code median household income, with the lowest income quartile used as the reference group.  Additional covariates in the model included urbanicity, region of the country, and age.

Results:  The final model for females (n=186,069) showed that the incidence of PTSD among individuals in each quartile was statistically significantly different than the rate in the lowest income quartile.  In addition, a dosing effect appeared in that the greater the neighborhood income, the higher the likelihood of experiencing an emergency room admission for PTSD ranging from a 30% increase for the second quartile (OR=1.29, 95% CI: 1.12, 1.48), to a 44% increase for the third quartile (OR=1.44, 95% CI: 1.25, 1.65) to an 88% increase for the highest quartile (OR=1.88, 95% CI: 1.59, 2.22) as compared to the lowest income quartile.  A similar trend emerged for males (n=197,869). While the second income quartile was not statistically significantly different from the first (OR=1.05, 95% CI: 0.89, 1.25), both the third and fourth mirrored the dosing effect found among females (OR=1.39, 95% CI: 1.18, 1.64; OR=2.02, 95% CI: 1.67, 2.43, respectively).

Conclusion and Implications: Researchers and practitioners are beginning to recognize that PTSD among the civilian population is an important issue of concern.  Furthermore, more attention is being paid to the role of environmental factors in triggering PTSD.  This study begins to expand existing research on PTSD beyond low-income neighborhoods and suggests that additional studies should focus on broader socio-economic environmental factors that may influence incidence rates of PTSD among children.