on Performance of Screening Mammography in a Large Community-based Population 1

Purpose: To evaluate the effect of comparison mammograms on accu-racy, sensitivity, specifi city, positive predictive value (PPV 1), and cancer detection rate (CDR) of screening mammogra-phy to determine the role played by identifi cation of change on comparison mammograms. Materials and Methods: This HIPAA-compliant and institutional review board– approved prospective study was performed with waiver of patient informed consent. A total of 1 157 980 screening mammograms obtained between 1994 and 2008 in 435 183 women aged at least 40 years were included. Radiologists recorded presence of comparison mammograms and change, if seen. Women were followed for 1 year to monitor cancer occurrence. Performance measurements were cal