Elimination of Cost Sharing for Screening Mammography in Medicare Advantage Plans

Abstract

Background: The Affordable Care Act (ACA) required most insurers and the Medicare program to eliminate cost sharing for screening mammography.

Methods: We conducted a difference-in-differences study of biennial screening mammography among 15,085 women 65 to 74 years of age in 24 Medicare Advantage plans that eliminated cost sharing to provide full coverage for screening mammography, as compared with 52,035 women in 48 matched control plans that had and maintained full coverage.

Results: In plans that eliminated cost sharing, adjusted rates of biennial screening mammography increased from 59.9% (95% confidence interval [CI], 54.9 to 65.0) in the 2-year period before cost-sharing elimination to 65.4% (95% CI, 61.8 to 69.0) in the 2-year period thereafter. In control plans, the rates of biennial mammography were 73.1% (95% CI, 69.2 to 77.0) and 72.8% (95% CI, 69.7 to 76.0) during the same periods, yielding a difference in differences of 5.7 percentage points (95% CI, 3.0 to 8.4). The difference in differences was 9.8 percentage points (95% CI, 4.5 to 15.2) among women living in the areas with the highest quartile of educational attainment versus 4.3 percentage points (95% CI, 0.2 to 8.4) among women in the lowest quartile. As indicated by the difference-in-differences estimates, after the elimination of cost sharing, the rate of biennial mammography increased by 6.5 percentage points (95% CI, 3.7 to 9.4) for white women and 8.4 percentage points (95% CI, 2.5 to 14.4) for black women but was almost unchanged for Hispanic women (0.4 percentage points; 95% CI, -7.3 to 8.1).

Conclusions: The elimination of cost sharing for screening mammography under the ACA was associated with an increase in rates of use of this service among older women for whom screening is recommended. The effect was attenuated among women living in areas with lower educational attainment and was negligible among Hispanic women. (Funded by the National Institute on Aging.).

Figure 1. Trends in Adjusted Rates of Biennial Screening Mammography in Intervention and Control Plans

Intervention plans were 24 Medicare Advantage plans that eliminated cost sharing for mammography, and control plans were 48 matched Medicare Advantage plans that maintained full coverage of mammography.

Figure 2. Adjusted Difference-in-Differences Estimates for Rates of Biennial Screening Mammography across 24 Matched Groups of Intervention and Control Plans

Shown are point estimates and corresponding 95% confidence intervals for adjusted difference-in-differences estimates (arranged in ascending order) comparing each intervention plan with the two matched control plans in the 2-year period before and the 2-year period after the elimination of cost sharing. Values greater than zero (above the dashed line) indicate increases in screening mammography rates for the intervention plan as compared with the matched control plans.