Multilevel Small Area Estimation for County-Level Prevalence of Mammography Use in the United States Using 2018 Data.

The U.S. Preventive Services Task Force recommends biennial screening mammography for average-risk women aged 50-74 years. We aim to generate county-level prevalence estimates for mammography use to examine disparities among counties. We used data from the 2018 Behavioral Risk Factor Surveillance System (BRFSS) ( = 111,902 women) and linked them to county-level data from the American Community Survey. We defined two outcomes: mammography within the past 2 years (current); and mammography 5 or more years ago or never (rarely or never). We poststratified the data with U.S. Census estimated county population counts, ran Monte Carlo simulations, and generated county-level estimates. We aggregated estimates to state and national levels. We validated internal consistency between our model-based and BRFSS state estimates using Spearman and Pearson correlation coefficients. Nationally, more than three in four women [78.7% (95% confidence interval {CI}: 78.2%-79.2%)] were current with mammography, although with large variations among counties. Also, nationally, about one in nine women [11% (95% CI: 10.8%-11.3%)] rarely or never had a mammogram. County estimates for being current ranged from 60.4% in New Mexico to 86.9% in Hawaii. Rarely or never having a mammogram ranged from 6% in Connecticut to 23.0% in Alaska, and on average, almost one in eight women in all the counties. Internal consistency correlation coefficient tests were ≥0.94. Our analyses identified marked county variations in mammography use across the country among women aged 50-74 years. We generated estimates for all counties, which may be helpful for targeted outreach to increase mammography uptake.