Relationship between clinical conditions and use of veterans affairs health care among Medicare-enrolled veterans

The Veterans Affairs (VA) Health Care System is the largest integrated health care system in the United States, with a medical care and research budget of U.S.$32.5 billion in fiscal year (FY) 2005. More than 5.4 million veterans received care in the VA in FY 2005. Although the Veterans Health Administration (VHA) has the responsibility to provide comprehensive medical care to veterans, many veterans have multiple options for medical care and may choose to use other health systems in addition to or instead of the VA. Medicare is one such alternative to the VA system. In FY 1999, 35 percent of veterans qualified for Medicare coverage due to age (65 and older), and 7 percent of veterans (who were younger than 65 years) were eligible for Medicare through Social Security Disability benefits, for a total of 42 percent of Veterans having Medicare eligibility (VA Information Resource Center 2003). Previous research shows that dually enrolled veterans make use of VA health care as well as non-VA health care under Medicare financing, possibly in a complementary manner (Shen et al. 2003; Rosen et al. 2005; Keyhani et al. 2007;). There are a number of factors that may affect an individual's choice about where to obtain health care when there is more than one option. Figure 1 illustrates a conceptual model of possible factors affecting patients' selection of a health care system. Our framework posits that access to a health care system, individual demographic characteristics, individual medical conditions, and health care system attributes will affect decisions about health system use. Figure 1 Factors Influencing Choice of Health Care System Specific aspects of access to a health care system include distance to health care facilities and coverage in the system. Research has found that the further the distance to the nearest VA hospital or clinic, the less likely it is that veterans will come to the VA for medical, surgical, or primary care (Burgess and DeFiore 1994; Mooney et al. 2000; Hynes et al. 2007;). Further distance from VA facilities also predicted lower utilization of VA transplant care (Weeks and West 2007), mental health and substance abuse (MH/SA) services (McCarthy et al. 2007; Carey et al. 2008;), and stroke care among dually enrolled veterans (Shen et al. 2008). For MH/SA services, Carey et al. (2008) found that as the distance to VA facilities increased, VA expenditures decreased, and a complementary result is seen for reduced access to Medicare facilities (Carey et al. 2008). Because health care under Medicare financing can be obtained in more locations than VA care (due to the limited number of VA facilities), residence in a rural versus urban setting may also be a determinant of where veterans receive their health care. Regarding the coverage aspect of access, the amount of out-of-pocket costs that an individual faces may also affect choice of health care system. A study by Shen et al. (2003) showed that dually enrolled veterans who have private Medicare supplemental insurance (Medigap) are more likely to use Medicare than the VA. In the VA setting, priority level for services (assigned based on the veteran's severity of service-connected disabilities and income level) is a proxy for coverage and out-of-pocket cost, and higher priority veterans (those who face less in out-of-pocket expenses) have been shown to be more likely to rely on the VA for health care (Hynes et al. 2007). The choice of whether to obtain VA versus non-VA health care may also be affected by specific medical conditions, and thus need for treatment of these conditions. Studies of dually eligible veterans have found that the majority of VA users hospitalized for acute myocardial infarction (Wright et al. 1997, 1999) and stroke (Shen et al. 2008) were admitted to Medicare hospitals, rather than VA hospitals, for their initial care. Over 80 percent of coronary revascularization procedures done for dually eligible veterans in New York during 1999 and 2000 were performed outside of the VA system (Weeks et al. 2006). In addition, Medicare-eligible veterans obtain the vast majority (86 percent) of solid-organ (liver, kidney, and heart) transplants through Medicare coverage, rather than within the VA health care system (Weeks and West 2007). On the other hand, for less acute conditions, over 94 percent of dually enrolled veterans with a MH/SA diagnosis use VA MH/SA services, while fewer than 28 percent of these veterans use Medicare for MH/SA services (Carey et al. 2008). Such prior research in this area lends credence to the notion that decisions about health care use may be driven by particular ailments. However, the extent to which various medical conditions concurrently influence VA versus Medicare use has not been comprehensively studied. Therefore, in the present study we examine the effect of a variety of factors on the proportion of care obtained from the VA (VA Reliance) among veterans enrolled in both the VA and Medicare. Our research is an important advance over previous research in a number of ways. First, we include all dually enrolled users of the VA health system, rather than restricting our focus to a specific disease or treatment, and we explore the association of health care system reliance with a comprehensive set of disease conditions as classified by aggregated condition categories (ACCs). Our cost calculations on the Medicare side include patient out-of-pocket and supplemental insurance payments; this reflects the higher cost sharing that Medicare users face and which are also part of the system costs. We include demographic and access variables—including gender, differential distance between VA and non-VA facilities, and VA priority level—that may contribute to use of one or both settings, and we examine the interaction between these factors and the ACCs. Finally, our study separately considers the younger Medicare-disabled and the Medicare-elderly populations, as individual characteristics, illness conditions, and patterns of utilization are different for these groups.