Burden of Catastrophic Health Expenditures for Acute Myocardial Infarction and Stroke Among Uninsured in the United States.

Acute myocardial infarction (AMI) and stroke are unanticipated major healthcare events that require emergent and expensive care. Given the potential financial implications of AMI and stroke among uninsured patients, we sought to evaluate rates of catastrophic healthcare expenditures (CHEs), defined as expenses beyond financial means, in a period before the implementation of insurance expansion and protections in the Affordable Care Act.1 In a large, nationally representative database of inpatient hospitalizations, the National Inpatient Sample, we identified all AMI (Clinical Classification Software code 100 as the primary diagnosis) and stroke (International Classification of Diseases, Ninth Revision codes 430, 431, 432.x, 433.x1, 434.x1, or 436 as the primary diagnosis) hospitalizations among uninsured nonelderly adults (age,18–64 years) between 2008 and 2012. To estimate patient expenses relative to income, we obtained 2 data components from the National Inpatient Sample: hospitalization charges and an ordinal variable (value of 1–4) representing quartiles of median income based on residential ZIP code. However, patient incomes can vary widely for each income quartile, and assessing CHEs requires an estimate of patient-level income. Therefore, using a previously suggested microsimulation model for assessing patient-level income from community income quartiles,2,3 we estimated income for each patient from a 2-parameter gamma probability distribution. We used the US Gini coefficient (a measure of income inequality) of 0.411 to define the shape parameter and the community-level income corresponding to each quartile to define the scale parameter for the income curve for each quartile (Figure, A).4 As previously suggested, to prevent overestimation of CHE as a result of an underestimation of income, mean quartile income values were centered at the highest value of the quartile range for quartiles 1 to 3 and at 80% of the upper bound for quartile 4.3 Annual food expenditures were derived from US Bureau of Labor Statistics estimates of food-related expenses as a function of income.5 Postsubsistence income was the difference between income and food-related subsistence expenses. On the basis of previous literature,3 a hospitalization charge was classified as a CHE if charges exceeded 40% of the postsubsistence income. Bootstrapped means and 95% confidence intervals were obtained by repeating the model over 10 000 simulations. All estimates were indexed to the year 2012 on the basis of the Consumer Price Index. National estimates were obtained with survey-analysis tools in SAS 9.4 (SAS Institute Inc, Cary, NC). We identified 39 296 AMI (81% patients ≥45 years of age, 26% women, 13% blacks, 38% in lowest income quartile, and 12% in highest quartile) and 29 182 stroke (82% patients ≥45 years of age, 39% women, 26% blacks, 41% in lowest income quartile, and 11% in highest quartile) hospitalizations among uninsured nonelderly, corresponding to 188 192 and 139 687 nationally. The uninsured represented 15% of both AMI and stroke hospitalizations among nonelderly. Median hospitalization charges Rohan Khera, MD* Jonathan C. Hong, MD, MHS* Anshul Saxena, PhD Alejandro Arrieta, PhD Salim S. Virani, MD, PhD Ron Blankstein, MD James A. de Lemos, MD Harlan M. Krumholz, MD, SM Khurram Nasir, MD, MPH