Abstract
Performance characteristics of mammography readers influenced the performance of pairs, but specific pairing strategies did not result in significantly different overall performance compared with that resulting from random pairing strategies.

Background
Despite variation in performance characteristics among radiologists, the pairing of radiologists for the double reading of screening mammograms is performed randomly. It is unknown how to optimize pairing to improve screening performance.

Purpose
To investigate whether radiologist performance characteristics can be used to determine the optimal set of pairs of radiologists to double read screening mammograms for improved accuracy.

Materials and Methods
This retrospective study was performed with reading outcomes from breast cancer screening programs in Sweden (2008–2015), England (2012–2014), and Norway (2004–2018). Cancer detection rates (CDRs) and abnormal interpretation rates (AIRs) were calculated, with AIR defined as either reader flagging an examination as abnormal. Individual readers were divided into performance categories based on their high and low CDR and AIR. The performance of individuals determined the classification of pairs. Random pair performance, for which any type of pair was equally represented, was compared with the performance of specific pairing strategies, which consisted of pairs of readers who were either opposite or similar in AIR and/or CDR.

Results
Based on a minimum number of examinations per reader and per pair, the final study sample consisted of 3 592 414 examinations (Sweden, n = 965 263; England, n = 837 048; Norway, n = 1 790 103). The overall AIRs and CDRs for all specific pairing strategies (Sweden AIR range, 45.5–56.9 per 1000 examinations and CDR range, 3.1–3.6 per 1000; England AIR range, 68.2–70.5 per 1000 and CDR range, 8.9–9.4 per 1000; Norway AIR range, 81.6–88.1 per 1000 and CDR range, 6.1–6.8 per 1000) were not significantly different from the random pairing strategy (Sweden AIR, 54.1 per 1000 examinations and CDR, 3.3 per 1000; England AIR, 69.3 per 1000 and CDR, 9.1 per 1000; Norway AIR, 84.1 per 1000 and CDR, 6.3 per 1000).

Conclusion
Pairing a set of readers based on different pairing strategies did not show a significant difference in screening performance when compared with random pairing.