SCREENING MAMMOGRAPHY - EXPERIENCE IN A HEALTH MAINTENANCE ORGANIZATION

PURPOSE: To evaluate (a) the relationship between mammogram interpreta tion and diagnosis of new breast cancer and (b) interprovider variatio n 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 cate gorized (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, a nd 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 interp retation was strongly associated with the diagnosis of new breast canc er; in 47.5% cases of category 5 mammograms, breast cancer was diagnos ed. There was substantial interprovider variation in the percentages o f category 3, 4, or 5 mammograms read. The percentage of category 4 an d 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 b etween a mammographic abnormality suggestive of cancer and its detecti on; however, substantial interprovider variation in the reading of cat egory 3, 4, and 5 mammograms and their positive predictive values exis ted. Reduction of interprovider variation should improve quality of ca re because the number of false-negative and false-positive mammograms should decrease.