Discrepant screening mammography assessments at blinded and non-blinded double reading: impact of arbitration by a third reader on screening outcome

To determine the value of adding a third reader for arbitration of discrepant screening mammography assessments.

We included a consecutive series of 84,927 digital screening mammograms, double read in a blinded or non-blinded fashion. Arbitration was retrospectively performed by a third screening radiologist. Two years' follow-up was performed.

Discrepant readings comprised 57.2 % (830/1452) and 29.1 % (346/1188) of recalls at blinded and non-blinded double readings, respectively. At blinded double reading, arbitration would have decreased recall rate (3.4 to 2.2 %, p <0.001) and programme sensitivity (83.2 to 76.0 %, p = 0.013), would not have influenced the cancer detection rate (CDR; 7.5 to 6.8 per 1,000 screens, p = 0.258) and would have increased the positive predictive value of recall (PPV; 22.3 to 31.2 %, p <0.001). At non-blinded double reading, arbitration would have decreased recall rate (2.8 to 2.3 %, p <0.001) and increased PPV (23.2 to 27.5 %, p = 0.021), but would not have affected CDR (6.6 to 6.3 per 1,000 screens, p = 0.604) and programme sensitivity (76.0 to 72.7 %, p = 0.308).

Arbitration of discrepant screening mammography assessments is a good tool to improve recall rate and PPV, but is not desirable as it reduces the programme sensitivity at blinded double reading.

Blinded double reading results in higher programme sensitivity than non-blinded reading.

Discrepant readings occur more often at blinded compared to non-blinded reading.

Arbitration of discrepant readings reduces the recall rate and PPV.

Arbitration would reduce the programme sensitivity at blinded double reading.