Geographic access and the use of screening mammography

Abstract

Background: Screening mammography rates vary geographically and have recently declined. Inadequate mammography resources in some areas may impair access to this technology. We assessed the relationship between availability of mammography machines and the use of screening.

Methods: The location and number of all mammography machines in the United States were identified from US Food and Drug Administration records of certified facilities. Inadequate capacity was defined as <1.2 mammography machines per 10,000 women age 40 or older, the threshold required to meet the Healthy People 2010 target screening rate. The impact of capacity on utilization was evaluated in 2 cohorts: female respondents age 40 or older to the 2006 Behavioral Risk Factor Surveillance System survey (BRFSS) and a 5% nationwide sample of female Medicare beneficiaries age 65 or older in 2004-2005.

Results: About 9% of women in the BRFSS cohort and 13% of women in the Medicare cohort lived in counties with <1.2 mammography machines per 10,000 women age 40 or older. In both cohorts, residence in a county with inadequate mammography capacity was associated with lower odds of a recent mammogram (adjusted odds ratio in BRFSS: 0.89, 95% CI: 0.80-0.98, P < 0.05; adjusted odds ratio in Medicare: 0.86, 95% CI: 0.85-0.87, P < 0.05), controlling for demographic and health care characteristics.

Conclusion: In counties with few or no mammography machines, limited availability of imaging resources may be a barrier to screening. Efforts to increase the number of machines in low-capacity areas may improve mammography rates and reduce geographic disparities in breast cancer screening.

Figure 1. Geographic Distribution of Mammography Capacity in US Countries, 2004

The number of mammography machines in each county was determined from mammography facility certification records and inspection reports from the US Food and Drug Administration.

Figure 2. Adjusted Odds Ratio for Impact of Inadequate Mammography Capacity on Receipt of Recent Mammogram, BRFSS and Medicare

BRFSS: Behavioral Risk Factor Surveillance System Survey Recent use of mammography defined by self-report receipt of a mammogram within the past two years (BRFSS, 2006) or health insurance claim for mammography in two-year period (Medicare, 2004–2005). In BRFSS analysis, odds ratios were adjusted for age, race, marital status, educational attainment, household income, health insurance, regular source of health care and check-up in the past 2 years. In Medicare analysis, odds ratios were adjusted for age, race, comorbidity and primary care visit during the two-year study period. All BRFSS estimates were weighted to account for the probability of sample selection and for post-stratification adjustment for non-response and non-coverage of households without telephones.