Dr. Ross points out that our recent study defined insurance status on the basis of the patient's primary insurance provider. Data on the provision of secondary insurance coverage were not collected before 2003. As a result, we cannot distinguish Medicaid patients who were also enrolled in managed care programs or who had dual Medicaid and Medicare coverage. After November 2003, we collected data on multiple insurers but grouped patients in a hierarchy based on 1) managed care, 2) Medicare, and 3) Medicaid. Thus, Dr. Ross is correct in stating that this strategy may have excluded Medicaid patients who had additional managed care insurance. Our Medicaid study population may be slightly sicker or may have poorer socioeconomic status than Medicaid patients covered by managed care. Despite this, our analysis did adjust extensively for baseline demographic characteristics, disease severity, and comorbid illnesses. Even after this adjustment, we found statistically significant differences in both the use of evidence-based care medications and in-hospital outcomes among Medicaid patients versus patients with managed care insurance. While these results may or may not be generalizable to Medicaid or managed care, they are certainly reflective of the large proportion of Medicaid patients who are not covered by managed care. In our opinion, these findings highlight a sizable underserved patient population and a highly important concern to health care providers and policymakers.