Role of Health Insurance Status in Interfacility Transfers of Patients With ST-Elevation Myocardial Infarction

Abstract

Lack of health insurance is associated with interfacility transfer from emergency departments for several nonemergent conditions, but its association with transfers for ST-elevation myocardial infarction (STEMI), which requires timely definitive care for optimal outcomes, is unknown. Our objective was to determine whether insurance status is a predictor of interfacility transfer for emergency department visits with STEMI. We analyzed data from the 2006 to 2011 Nationwide Emergency Department Sample examining all emergency department visits for patients age 18 years and older with a diagnosis of STEMI and a disposition of interfacility transfer or hospitalization at the same institution. For emergency department visits with STEMI, our multivariate logistic regression model included emergency department disposition status (interfacility transfer vs hospitalization at the same institution) as the primary outcome, and insurance status (none vs any [including Medicare, Medicaid, and private insurance]) as the primary exposure. We found that among 1,377,827 emergency department STEMI visits, including 249,294 (18.1%) transfers, patients without health insurance (adjusted odds ratio 1.6, 95% CI 1.5 to 1.7) were more likely to be transferred than those with insurance. Lack of health insurance status was also an independent risk factor for transfer compared with each subcategory of health insurance, including Medicare, Medicaid, and private insurance. In conclusion, among patients presenting to United States emergency departments with STEMI, lack of insurance was an independent predictor of interfacility transfer. In conclusion, because interfacility transfer is associated with longer delays to definitive STEMI therapy than treatment at the same facility, lack of health insurance may lead to important health disparities among patients with STEMI.

Figure 1

Flow chart of emergency department patient visits used in the study. Flow chart for included emergency department visits with an ST-elevation myocardial infarction diagnosis in the Nationwide Emergency Department Sample for years 2006 – 2011. Each model is determined by inter-facility transfer rate and excludes patients with unknown insurance status, and a disposition status of discharged, died in the emergency department, or unknown.

Figure 2

Percentage of emergency department visits transferred by insurance status. Unadjusted percentage of emergency department visits for ST-elevation myocardial infarction in the United States that resulted in inter-facility transfer by year for all hospitals. Error bars represent 95% confidence intervals.

Figure 3

Predicted probability of inter-facility transfer for emergency department visits with ST-elevation myocardial infarction vs (a) Emergency department annual visit volume and (b) patient age, by year. Sample predicted probability plots of inter-facility transfer for emergency department visits with ST-elevation myocardial infarction by study year according to a) annual emergency department volume; and b) patient age at time of presentation to the emergency department. Plots were calculated from the multivariable regression model with other independent variables in the model fixed at the following values: trauma center, urban setting, women, West region, median household income in patient's zip code ≥$67,000, uninsured, median age of 65 years, and median annual emergency department volume of 22,135 visits per year. The shaded area represents the 95% confidence interval

Figure 3

Predicted probability of inter-facility transfer for emergency department visits with ST-elevation myocardial infarction vs (a) Emergency department annual visit volume and (b) patient age, by year. Sample predicted probability plots of inter-facility transfer for emergency department visits with ST-elevation myocardial infarction by study year according to a) annual emergency department volume; and b) patient age at time of presentation to the emergency department. Plots were calculated from the multivariable regression model with other independent variables in the model fixed at the following values: trauma center, urban setting, women, West region, median household income in patient's zip code ≥$67,000, uninsured, median age of 65 years, and median annual emergency department volume of 22,135 visits per year. The shaded area represents the 95% confidence interval