Obtaining previous mammograms for comparison: usefulness and costs.

Abstract

We undertook a study to evaluate the usefulness and the cost of our policy of obtaining all previous mammograms, whether done at our facility or another, for purposes of comparison with current mammographic examinations. We reviewed 1432 randomly selected screening mammography examinations from the year 1992. Information collected included whether there were previous mammograms, whether they could be obtained, the clinical impact of the comparisons, and the time and cost of obtaining the earlier mammograms. Of the 1432 cases, 1245 women (87%) had had previous mammograms: 971 (78%) of these were done at our institution (all but 12 were available for comparison) or were brought in by the woman at the time of her scheduled examination; 274 (22%) were done elsewhere and were not available at the time of the examination. Of the latter 274 examinations, 140 (51%) could not be obtained despite vigorous efforts. Clinical management was affected as a result of comparison in 35 of the 1093 cases in which previous mammograms were obtained: seven biopsies were performed (four benign, two malignant, one pending), 10 imaging workups or follow-ups were initiated, two biopsies were avoided, and 16 imaging workups or short-term follow-ups were avoided. The two cancers that were detected as a result of obtaining previous films included one manifested by an increase in calcifications and one by a neodensity that was recognized in retrospect in an otherwise normal mammogram. The average labor and postage cost for each outside mammogram requested and received was $12.52; if the film was requested but not received, the average labor cost was $5.33. When interpreting mammograms, a comparison with previous examinations has a positive impact on clinical management and cancer detection in a limited number of cases. The overall costs and time involved in obtaining previous mammograms from other facilities are substantial. The previous mammograms cannot be obtained in all cases, and in our study only 50% of the mammograms done at other facilities could be obtained. These issues need additional consideration before binding policies are established.