Commentary—anatomy of racial disparity in influenza vaccination

Health Services Research, April, 2005 by Kevin Fiscella

The Institute of Medicine report, Unequal Treatment, documents the presence of racial/ethnic disparities in health care across multiple procedures. It concluded that stereotyping, biases, and uncertainty on the part of health care providers all contribute to unequal treatment while also acknowledging the role of access and patient factors (Institute of Medicine 2002). Yet, despite the large number of studies documenting disparities in health care, few have sought to quantify the relative role of provider, patient, and access factors to disparities.

Large racial/ethnic disparities have been consistently documented in use of expensive, invasive technology including coronary revascularization procedures (Epstein et al. 2003), organ transplantation (Ayanian et al. 1999; Epstein et al. 2000), cerebrovascularization management and treatment (Lillie-Blanton et al. 2002), and knee and hip arthroplasty (Institute of Medicine 2002; Skinner et al. 2003). Disparities have been less consistently documented in the provision of primary care procedures. For example racial/ethnic disparities in screening for breast, cervical, colon, and prostate cancer range from small to nonsignificant (Swan et al. 2003). A study of directly observed primary care visits showed no evidence in racial disparity in care (Williams, Flocke, and Stange 2001). However, elderly African Americans and Hispanics consistently report lower rates of influenza vaccines. In 2002, only 48.5 percent of elderly African Americans and 50.7 percent of Hispanics reported receiving the vaccine compared with 69.6 percent of whites (Centers for Disease Control and Prevention 2003).

IMPORTANCE OF DISPARITIES IN FLU VACCINE

Disparity in influenza vaccination has a substantial impact on minority population health. In recent years, influenza has accounted for upwards of 50,000 deaths annually (Thompson et al. 2003). Ninety percent of these deaths occur among the elderly and most are cardiovascular related (Thompson et al. 2003). Vaccination reduces overall mortality including deaths from cardiovascular disease from influenza by 30 percent (Gross et al. 1995). Based on estimated 2.9 million elderly African Americans and 2.1 million elderly Hispanics, the elimination of racial and ethnic disparity in influenza vaccination would result in an additional 1 million elderly minority persons being vaccinated. Thus, it is plausible that disparity in influenza vaccination not only contributes to racial and/or ethnic disparity in influenza/pneumonia deaths but also to racial disparity in deaths from cardiovascular disease, cerebrovascular disease, and diabetes (Valdez et al. 1999; Nichol et al. 2003).

Disparity in influenza vaccination also represents a useful model for improved understanding of disparities in health care. Influenza vaccines are administered frequently enough and disparity is sufficiently large so that enormous samples are not required to examine causes. No referral is required for vaccination. Following informed consent of the risks and benefits, the intervention is immediately administered, obviating the need for further patient follow-up or adherence.

POTENTIAL CAUSES OF DISPARITIES

Despite compelling reasons for studying it, little attention has been given to examining the causes of this disparity. The causes of these disparities are not known. As with most disparities in health care, potential explanations for disparity in influenza vaccination can be grouped into at least five major categories. First, less frequent use of care because of various access barriers could contribute to disparities. African Americans and Hispanics have fewer office visits than non-Hispanic whites (Greenblatt 2003), so they have less opportunity to receive a particular intervention. Second, controlling for age, minorities report worse health status and more comorbidities than whites (Ren and Amick 1996; McGee et al. 1996; Ostchega et al. 2000). In theory, this should result in higher vaccination rates based on higher risk status. In practice, other conditions compete for providers' time and attention and patients with greater morbidity often receive less preventive care (Nutting et al. 2001). African Americans and Hispanics have lower educational levels than whites and education level is a strong predictor of receipt of preventive care (Swan et al. 2003). Third, patients' knowledge and attitude toward the intervention might differ by race and ethnicity. For example, some studies suggest that African Americans are more risk averse (Shapiro et al. 1969; Oddone et al. 1998) and more concerned about being experimented upon by physicians without their knowledge or consent than whites (Corbie-Smith, Thomas, and St George 2002). Fourth, unconscious provider bias may affect delivery of care so that a provider may be more likely to vaccinate a white rather than a minority patient. Last, minority patients may see providers who are less inclined to administer these vaccinations. Distinguishing these competing explanations is critical to the design of interventions to address these disparities.