Geographic variations in utilization of screening mammography by Medicare beneficiaries: Potential policy implications for racial disparities

Background: For many cogent reasons, including additional barriers among blacks, we hypothesized that Medicare's 1991 decision to reimburse providers for screening mammography produced more rapid diffusion of benefits to whites.

Objective: Describe regular screening mammography (> 1 per two years for women 65-74 years) in 1992-1995 (T1) and 2005-2008 (T2) among non-Hispanic black and white Medicare beneficiaries.

Methods: Two cohorts of 1,000,000 women, each of whom were alive from 1992-95 or 2005-08, were obtained from all Medicare beneficiaries using complex probability sampling to enrich Black inclusion. Screening mammography was identified with an adapted Smith-Bindman algorithm.

Results: There were 153,857(T1) and 128,919(T2) blacks, and 465,669(T1) and 403,085(T2) whites ages 65-74. Absolute improvement in regular screening was 16% (31% in T1 to 47% in T2). The absolute black increase of 15% (21%-36%) was significantly higher than the white increase of 13% (32%-45%). However, blacks exceeded whites only in the Southern US (17% to 12%). Elsewhere, black improvement was 14% (22% to 36%), which was significantly lower than white improvement of 17% (32% to 49%). Also whites exceeded blacks in the Northeast, Midwest and West. Western black outcomes were particularly poor, driven by improvement of only 8% in Los Angeles County, CA.

Conclusions: While regular screening improved for both races, significant geographic variations, particularly as regards higher white utilization outside the Southern US, were obscured by national trends. These data are consistent with the hypothesis that Medicare may contribute to racial disparities in recommended screening mammography in most areas of the country.