The causes of racial and ethnic differences in influenza vaccination rates among elderly medicare beneficiaries

Health Services Research, April, 2005 by Paul L. Hebert, Kevin D. Frick, Robert L. Kane, A. Marshall McBean

Influenza outbreaks occur nearly every year and cause significant excess medical costs (McBean, Babish, and Warren 1993), as well as an average of 36,000 excess deaths, mostly among the elderly (Bridges et al. 2003). Influenza vaccination has been shown to significantly reduce influenza-related morbidity and mortality (Bridges et al. 2003), and the Advisory Committee on Immunization Practices recommends that nearly all persons over the age of 50 receive annual vaccination (Bridges et al. 2003). Since 1993, Medicare has covered the full cost of influenza vaccination.

While the Healthy People 2000 goal of 60 percent influenza vaccination among the elderly has been met at the national level, significant racial disparities persist (CDC 2003a, b). Behavioral Risk Factor Surveillance System (BRFSS) data for 2000 and 2001 combined indicate rates of 66.0 percent among elderly non Hispanic whites, 48.3% among non-Hispanic blacks, and 53.7 percent among Hispanics (CDC 2003a). National Health Interview Survey data indicate similar rates in 2002 of 69.6, 48.5, and 50.7 percent, respectively (CDC 2003b). Elimination of these disparities is a goal of Healthy People 2010 (HHS 1999) and the Racial and Ethnic Adult Disparities in Immunization Initiative (READII) at the Department of Health and Human Services (HHS 2002). This work is made more difficult because the causes of the disparity are poorly understood and the effectiveness of strategies to in crease immunizations has not been established in minority populations. Meta-analyses (Szilagyi et al. 2000; Stone et al. 2002) have documented the effectiveness of both patient-focused strategies, such as mailed reminders and patient education, and clinic based strategies, such as providing physician reminders and incentives, allocating space and personnel at clinics for the purpose of providing vaccinations, and empowering nurses to provide influenza vaccinations. However, many of these studies were conducted in areas with low minority populations, or used administrative databases that do not identify the race of the beneficiary. How well these strategies will work in minority populations, which may have different barriers to overcome, is not clear. For example, organizational changes at a clinic will have little effect on populations that access clinical care infrequently, and postcard reminders may have little effect on populations with resistant attitudes or beliefs regarding vaccination.

The purpose of this study was to identify the causes of racial and ethnic disparities in influenza vaccination in the elderly in order to better inform efforts to eliminate the disparity. We explored three possible causes of the disparity: (1) differences in resistant attitudes and beliefs regarding influenza vaccination, (2) differences in access to care during weeks when influenza vaccinations were given, and (3) discriminatory treatment of African-American and Hispanic patients by their providers.

METHODS

Data were from the Medicare Current Beneficiary Survey (MCBS) (Adler 1994) Access to Care and accompanying Medicare claims files for 1995 through 1996. The MCBS is an annual, in-person, rotating panel survey that elicits information on the health, health behaviors, and use of medical services for a panel of several thousand Medicare beneficiaries nationwide. We studied community-dwelling respondents [greater than or equal to] 65 years who completed both the 1995 and 1996 surveys. We defined vaccination status for the 1995-1996 influenza season by self-reported influenza vaccination use, which was elicited in the 1996 survey. Self-reported vaccine use is highly sensitive but only modestly specific when compared with medical records (Nichol, Korn, and Baum 1991 ; Mac Donald et al. 1999; Zimmerman, Raymund et al. 2003). We defined three racial groups according to the beneficiary's self-reported race and ethnicity: non-Hispanic white, non Hispanic African American, and Hispanic. For the remainder of the paper, the first two will be referred to as "white" and as "African American," respectively.

Resistant Attitudes and Beliefs

To address whether resistant attitudes and beliefs regarding influenza vaccination are a cause of racial disparities, we analyzed self-reported reasons for not receiving a vaccination. In the 1996 MCBS, participants who self-reported that they did not receive an influenza vaccination in 1995 were asked for all reasons they had not been vaccinated (CDC 1999). Interviewers assigned each reason to one of 13 categories (Table 1). We subjectively classified each category as reflecting resistance to vaccination if it suggested attitudes or beliefs about influenza vaccinations that might inhibit a beneficiary from accepting a free vaccination if one were offered. In a recent study, persons who agreed with statements in any of these resistant categories were far less likely to receive vaccination than were persons who did not hold these beliefs (Santibanez et al. 2002), although the study did not specifically address the role of race. We used this classification to code every MCBS participant as resistant or not resistant to vaccination. Persons who gave any resistant response were coded resistant. All others were coded as nonresistant. This had the effect of coding all self-reported vaccinees as nonresistant because only those who reported that they had not received vaccination were asked reasons for remaining unvaccinated.