Radiology, Vol 205, 441-445, Copyright © 1997 by Radiological Society of North America
Screening mammography: experience in a health maintenance organization
NA Hanchak, HB Kessler, S MacPherson, S Xuan and LJ Solin
Aetna US Healthcare, US Quality Algorithms, Blue Bell, PA 19422, USA.
PURPOSE: To evaluate (a) the relationship between mammogram interpretation
and diagnosis of new breast cancer and (b) interprovider variation in
mammogram interpretation. MATERIALS AND METHODS: Interpretations of
screening mammograms (133,668 mammograms in 114,899 women) acquired during
21 months in a large health maintenance organization were categorized
(categories 1-5) with use of a standard format. During 1 year after
mammography, new breast cancer was identified with use of claims data.
Interprovider variation in the categories read was evaluated, and
percentages of these categories were correlated with breast cancer
detection. RESULTS: Over the 21 months, 1,018 mammograms were followed by a
diagnosis of new breast cancer. The category of mammogram interpretation
was strongly associated with the diagnosis of new breast cancer; in 47.5%
cases of category 5 mammograms, breast cancer was diagnosed. There was
substantial interprovider variation in the percentages of category 3, 4, or
5 mammograms read. The percentage of category 4 and 5 mammograms read
correlated inversely with the likelihood of cancer detection (Pearson
correlation coefficient [r] = -.4778 after log-log transformation, P <
.001). CONCLUSION: A strong correlation existed between a mammographic
abnormality suggestive of cancer and its detection; however, substantial
interprovider variation in the reading of category 3, 4, and 5 mammograms
and their positive predictive values existed. Reduction of interprovider
variation should improve quality of care because the number of
false-negative and false-positive mammograms should decrease.
