Should double reading (with consensus or arbitration for discordant readings) vs. single reading be used to screen mammograms for early detection of breast cancer in organised population-based screening programmes?

The GDG suggests by consensus that double reading (with consensus or arbitration) over single reading be used to diagnose breast cancer in mammography screening.

Only one study with digital mammography was included in the evidence, which limited the GDG to be able to issue a strong recommendation.

The GDG notes that in the context of double reading with consensus or arbitration, no differences were observed in accuracy when arbitration or consensus or both were used to reconcile differences in interpretation between mammography readers.

• In settings with many low-volume mammography readers, the balance of benefits and harms may be even greater. The GDG refers readers to the PICO Question 7: ‘What is the optimal annual interpretive volume for radiologists reading screening mammograms?’ in the CCIB report, addressed by the QASDG regarding the experience level of mammography readers.
• In some settings, capacity (human resources of mammography readers) should be scaled up to implement double readings. In settings where double readings are already in practice, the GDG suggests continued use of double readings with consensus or arbitration.
• The GDG notes that a consideration that can favour double reading with consensus or arbitration is in those settings with many low volume mammography readers; the desirable effects of double reading with consensus or arbitration were found to be greater with less undesirable effects in these settings as compared to high volume mammography reader settings.

The GDG suggests reporting the proportion of double reading with consensus or arbitration of mammograms that occur in practice. The GDG refers this suggestion to the QASDG for consideration.

• The GDG suggests further research examining the cost-effectiveness of double vs single reading of digital mammography in different settings. Cost-effectiveness data was only identified for Spain.
• The GDG suggests new research using observational studies comparing double reading with consensus or arbitration with single reading in the context of digital mammography. Additional research could also be performed to assess accuracy within the context of double readings assessing a single reader vs with the addition of a second reader, which is performed in practice.
• The GDG suggests the use of formal radiologist blinding in research to improve the quality of evidence on double vs single readings.
• The GDG notes that newer screening strategies such as digital breast tomosynthesis (DBT) or automatic computer assisted detection (CAD) was excluded from the analysis of this question with double vs single mammography. Future research could assess the impact of double reading using CAD and/or DBT systems.