Comparing Previous Mammograms and Recall Rates

When radiologists compare two or more prior mammograms, screening mammography recall rates are significantly reduced, according to a study published in the American Journal of Roentgenology.

Researchers from the University of California, San Francisco, evaluated the effect of comparison with multiple prior mammograms on the outcomes of screening mammography relative to comparison with a single prior mammogram.

The researchers retrospectively analyzed 46,288 consecutive screening mammograms performed at the department of radiology and biomedical imaging, University of California, San Francisco, for 22,792 women. The examinations were divided into three groups: those interpreted without comparison with prior mammograms, those interpreted in comparison with one prior examination, and those interpreted in comparison with two or more prior examinations. The researchers then determined the rate of examination recall of each group, as well as the positive predictive value of recall for both the group of examinations compared with a single prior mammogram and the group compared with multiple prior mammograms.

The results showed that the recall rate for mammograms interpreted without comparison with prior examinations was 16.6%, whereas that for mammograms compared with one prior examination was 7.8%. Mammograms compared with two or more prior examinations was 6.3%. After adjustment was made for age, the odds ratio of recall for the group with multiple prior examinations relative to the group with a single prior examination was 0.864. Statistically significant increases in the PPV1 of 0.05 and in the cancer detection rate of 2.3 cases per 1000 examinations were also noted for mammograms compared with multiple prior examinations relative to those compared with a single prior examination.

"Our findings suggest that radiologists who make comparisons with more than one prior examination at screening mammography will have more true-positive outcomes and fewer false-positive outcomes," study co-author Kimberly M. Ray, MD, assistant professor, department of radiology, UCSF, said in a release.

"We have shown that the recall rate (percentage of cases with a potential abnormality that require additional imaging evaluation) for screening mammography decreases, whereas the positive predictive value of recall (PPV1) and the cancer detection rate increase when two or more prior examinations are used for comparison relative to comparison with a single prior examination," Ray said.