Independent Double Reading of Screening Mammograms

Abstract

Objective — To evaluate the cost effectiveness of independent double reading of screening mammograms. Setting — Prospective study of 18817 women undergoing first or repeat screening in a population based programme in the Florence district. Methods — Mammograms were independently double read by experienced radiologists. Subjects with mammographic abnormalities reported by at least one reader were recalled for diagnostic assessment. The mean increase in recall rate, cancer detection rate, and screening costs attributable to double reading was calculated. Results — Eleven of 125 cancers were detected by only one reader. The mean increase in cancer detection rate attributable to double reading compared with single reading was 4·6% (95% confidence interval (CI) 1·1 to 8·9). From a total of 748 cases referred for diagnostic assessment, 196 subjects were referred by one reader only. The mean increase in referral rate attributable to double reading compared with single reading was 15·1% (CI 12·3 to 17·8). Double reading caused a marked increase in the cost for each woman screened −8·5% at the first screening and 6·2% at repeat screening and a more limited increase in the cost for each cancer detected −3·5% at the first screening and 2·7% at repeat screening. Cancers detected by only one screener were at an earlier stage than those detected by both screeners (P = 0·6, not significant). Conclusions — Independent double reading results in only a modest increase in the detection of cancers and therefore may not be cost effective.