Mammography rates increased after the Affordable Care Act (ACA) eliminated cost sharing for preventive services recommended by the U.S. Preventive Services Task Force, according to a new study published by the New England Journal of Medicine.

“The elimination of cost sharing for preventive care was one of the first large-scale applications of value-based insurance design, which links the generosity of insurance coverage for a service to the value of that service in improving health,” wrote lead author Amal Trivedi, MD, with the Brown University School of Public Health, and colleagues.

The researchers looked at data on biennial screening mammography among more than 15,000 women 65 to 74 years of age in 24 Medicare Advantage plans that eliminated cost sharing and compared it with data from more than 52,000 women in 48 matched control plans that maintained full coverage.

The chief finding was that biennial screening mammography increased from 59 percent in the two-year period before the ACA mandate to 65 percent in the two-year period after plans had eliminated cost sharing. In the control plans, the rates of biennial screening were 73 percent in the pre-policy period to 72 percent in the post policy period.

“The median difference-in-differences estimate was six percentage points,” the authors wrote. “For 18 of the 24 groups, the difference-in-differences estimate was positive, indicating an increase in the rate of screening in the intervention plan as compared with the rates in matched control plans.”

The researchers also noted differences among race and ethnic groups, as well as income and educational levels. Biennial screening mammography increased by almost seven percent among white women, eight percent in black women, and there was a change of less than one percent in Hispanic women.

Women living in areas of lower educational attainment did not respond to the change in cost sharing, while there was an increase among women living in the highest quartile of educational attainment. Women living in areas in the lowest quartile of poverty showed a greater increase in screening rates at almost nine percent, but women living in the highest quartile of poverty showed only a two percent change.

The authors concluded their findings “support the importance of outreach to Hispanic women and socioeconomically vulnerable populations about reductions in cost sharing for preventative care and other similar value-based changes in insurance policies.”