Screening mammography use: the importance of a population perspective.

Mammography has been shown to be effective in decreasing breast cancer mortality. However, not all women receive recommended screening. The purpose of this study was to measure the effect of systemic health care delivery factors and patient demographic factors on the use of mammography among a population of women with insurance coverage for screening mammography. We studied 8,805 women, 50 to 74 years of age, who were members of a health maintenance organization in Michigan during 1992. Data were obtained from computerized patient registration and billing systems. Estimated household income was based on zip code and 1990 U.S. Census information. During the study period, 47% of the entire study population received a mammogram. Among the 4,628 women who did not receive a mammogram, 2,358 (51%) did not have any primary care visits in 1992, or did not have a visit at a time when they were due for mammography. Among women with at least one visit during 1992, 60% received a mammogram. Analysis of this group revealed that Caucasian race, married status, and higher estimated household income were associated with 3%-5% higher mammography rates (in absolute terms); seeing a gynecologist and attending a primary care clinic where mammography was available on site were associated with 10%-11% higher rates; and not having at least one of their primary care visits at a time when due for screening was associated with a 33.5% lower mammography rate. These differences persisted after adjusting for other variables. In this population, factors surrounding health care delivery, such as having an office visit when due for screening, the number of office visits, and having been seen by a gynecologist, had a greater association with mammography use than did demographic factors. A population-based perspective that includes developing outreach strategies for women overdue for screening, who have not visited their health care provider, is as important as further improvements in office-based strategies to increase breast cancer screening.