The role of arbitration of discordant reports at double reading of screening mammograms.

OBJECTIVE

To asses the effectiveness of arbitration of discordant double readings in mammography screening.

DESIGN

A retrospective study of 1217 consecutive arbitrations.

SETTING

A subset of discordant double readings from the Florence screening programme underwent arbitration by a third reader.

RESULTS

Positive arbitration of 1217 discordant double readings prompted assessment in 476 cases (39.2%), detecting 30 cancers (6.3%). Of 741 negative arbitrations (60.8%), 311 have been followed up thus far, and two cancers (0.64%) occurred in the site previously suspected at one of the two independent readings. Arbitration had a sensitivity of 86.3% and a negative predictive value of 99.3%. Arbitration reduced the overall referral rates from 3.82% to 2.59% (relative decrease 32.1%). Due to false-negative arbitration, cancers detected per 1000 women screened would decrease from 4.58 to 4.50 (relative decrease 1.7%). For every cancer missed due to false-negative arbitration, 151 unnecessary recalls and 21,248 euro would have been saved, whereas the saved cost per screened woman due to arbitration was 1.72 euro.

DISCUSSION

Arbitration of discordant double reading would substantially reduce referral rates with a limited reduction in cancer detection rate, and may be recommended as a routine procedure. Greater benefit from arbitration might be expected in the presence of high referral rates at independent double reading, a common scenario in a newly implemented service screening.