Measuring the performance of screening mammography in community practice with Medicare claims data

Few studies have examined the outcomes of screening mammography in community practice, particularly the extent of false positive exams among older asymptomatic women.

Subjects were female Medicare beneficiaries, age 67 or older, residing in one of eleven SEER areas, with no evidence of breast cancer. Medicare claims data were used to identify their screening mammograms over two time periods, 1993-1995 and 1996-1998, and to measure their use of follow-up diagnostic testing (diagnostic mammography, breast ultrasound and breast biopsy) within three months of the screening mammogram.

There were significant differences among the rates of diagnostic testing for each age group (67-74; 75+ ) by year, but no clear trend toward higher or lower rates over time. Although rates of diagnostic testing differed significantly by geographic region in both time periods 1993-1995 and 1996-1998, estimates of specificity for all regions were within AHRQ clinical practice guidelines (specificity greater than 90%). Specificity significantly improved with the volume of the radiologist's practice for the latter time period (1996-1998) but not for the former (1993-1995).

Medicare claims offer an accessible population-based source of data for mammography performance indicators. As such, they offer a low cost method for evaluating individual mammography practices as well as monitoring the impact of reimbursement policies, practice guidelines and laws mandating requirements for accrediting facilities.