Socioeconomic and racial/ethnic differences in the discussion of cancer screening: "between-" versus "within-" physician differences

Cancer is the leading cause of death in the United States for those younger than 85, surpassing cardiovascular disease (Jemal et al. 2005). Effective screening techniques are available for early stage detection of several major types of cancer such as colorectal cancer for men and women and breast and cervical cancer among women. Prostate cancer screening for men is effective although controversial. In recent years, increased public awareness and adherence to cancer screening guidelines have contributed to a continued decline in cancer death rates and improved 5-year survival (Jemal et al. 2004). However, the rate of adherence to cancer screening, like that for many other preventive services, is much lower among populations of low socioeconomic status (SES) compared with people on the higher rungs of the socioeconomic ladder (Ponce et al. 2003; National Center for Health Statistics 2004). Studies using data from the Surveillance, Epidemiology and End Results (SEER) Program of the National Cancer Institute have shown disparities in stage at diagnosis by income or poverty (Singh et al. 2003), occupation or profession (Schwartz et al. 2003) and insurance coverage (Roetzheim et al. 1999; McDavid et al. 2003). It is thus not surprising that a socioeconomic gradient in cancer mortality and survival exists. According to the National Healthcare Disparities Report (DHHS 2004), those with a high school education or less had higher mortality rates from almost all types of cancer compared with those with some college education. Differences in cancer survival by neighborhood poverty and by insurance status are also substantial (Singh et al. 2003; Bradley et al. 2005). Although racial/ethnic disparities in early stage diagnosis are less consistent across different types of cancer and across different minority groups relative to whites, mortality from all cancers is highest among blacks (DHHS 2004; Ward 2004).1 Disparities in adherence to cancer screening guidelines are partly due to racial/ethnic and socioeconomic disparities in access to health care. All major cancer screening procedures are either ordered by a physician (e.g., endoscopies for colorectal cancer screening and prostate-specific antigen test [PSA] test for prostate cancer) or performed in a physician's office (e.g., pap smear), making a visit to a physician's office or clinic a precondition for screening. However, disparities in cancer screening utilization exist even among people with a usual source of care or who regularly visit their physicians (for example, McMahon et al. 1999; also see Table 2). Studies have examined patient-reported barriers to cancer screening and found that a greater proportion of minority and low-SES persons cite “lack of awareness” and “not recommended by a doctor” as the main barriers (Finney, Nelson, and Meissner 2004), suggesting that racial/ethnic and SES disparities in physician–patient communication regarding cancer screening may have contributed to disparities in screening rates. Table 2 Unadjusted Rates of Cancer Screening Discussion by Patient Race/Ethnicity and SES (%) In this study, we examine two potential sources of disparities in discussion of several important types of cancer screening: (1) “between-physician” differences, which arise because racial/ethnic minority or low-SES patients receive care from different physicians than white patients or patients of higher SES, and (2) “within-physician” differences, which arise because patients of different race/ethnicity or SES receive different care from the same physicians. We make use of two unique data sets that match patients to their primary care physicians. This feature of these data enables us to study the relative importance of between- versus within- physician differences as causes of disparities in cancer screening discussion. Our data also enable us to identify the patient characteristics (race/ethnicity or the different aspects of SES) that are associated with between- or within- physician differences, which in turn sheds light on policies designed to close the racial/ethnic or socioeconomic gap in cancer and cancer screening.