Breast cancer screening in an insured population: whom are we missing?

Kaiser Permanente Colorado is an integrated health care system that uses automatic reminder programs and reduces barriers to access preventive services, including financial barriers. Breast cancer screening rates have not improved during the last five years, and rates differ between subgroups: for example, black and Latina women have lower rates of mammography screening than other racial groups.

We retrospectively evaluated data from 47,946 women age 52 to 69 years who had continuous membership for 24 months but had not undergone mammography. Poisson regression models estimated relative risk for the impact of self-identified race/ethnicity, socioeconomic characteristics, health status, and use of health care services on screening completion.

The distribution of race/ethnicity among unscreened women was 55.5% white, 7.0% Latina, and 3.7% black, but race/ethnicity data were missing for 29%. Of these, no record of race/ethnicity was available for 86.7%, and for 5.1%, the data request was recorded but the women declined to identify their race/ethnicity. Nonwhite ethnicity increased risk of screening failure if black, Latina, "other" (eg, American Indian), or missing race/ethnicity. Population-attributable risks were low for minorities compared with the group for whom race/ethnicity data was missing. A greater number of office visits in any setting was associated with greater likelihood of undergoing mammography. Women with missing race/ethnicity data had fewer visits and were less likely to have an identified primary care physician.

Greater improvement in mammography screening rates could be achieved in our population by increasing screening among women with missing race/ethnicity data, rather than by targeting those who are known to be of racial/ethnic minorities. Efforts to address screening disparities have been refocused on inreach and outreach to our "missing women."