Effect of a legislative mandate on mammography use and coding practices in Maryland

To analyze the effect of the 1991 Maryland legislative mandate of screening mammography benefits.

Claims submitted between January 1991 and December 1993 for outpatient mammograms obtained in women covered under Blue Cross Blue Shield of Maryland insurance indemnity contracts were analyzed for the distribution of services and charges.

For 184,723 women, 285,241 claims were submitted by 851 Maryland providers. Claims for "mammography bilateral," which were considered "diagnostic," represented 67%; 24% were submitted for "screening mammography bilateral," and 9% were submitted for "mammography unilateral." Mammography claims increased only 25% during the 3 years, despite an estimated fivefold increase in the number of women with the screening mammography benefit. Mammography coding shifted from bilateral to screening.

The number of mammograms obtained increased only modestly after the mandate, but claims coded for mammography bilateral declined dramatically. Removal of financial barriers appears to be insufficient to increase appropriate use of screening mammography.