Cost-Effectiveness of Double Reading versus Single Reading of Mammograms in a Breast Cancer Screening Programme

Abstract

Objectives: The usual practice in breast cancer screening programmes for mammogram interpretation is to perform double reading. However, little is known about its cost-effectiveness in the context of digital mammography. Our purpose was to evaluate the cost-effectiveness of double reading versus single reading of digital mammograms in a population-based breast cancer screening programme.

Methods: Data from 28,636 screened women was used to establish a decision-tree model and to compare three strategies: 1) double reading; 2) double reading for women in their first participation and single reading for women in their subsequent participations; and 3) single reading. We calculated the incremental cost-effectiveness ratio (ICER), which was defined as the expected cost per one additionally detected cancer. We performed a deterministic sensitivity analysis to test the robustness of the ICER.

Results: The detection rate of double reading (5.17‰) was similar to that of single reading (4.78‰; P = .768). The mean cost of each detected cancer was €8,912 for double reading and €8,287 for single reading. The ICER of double reading versus single reading was €16,684. The sensitivity analysis showed variations in the ICER according to the sensitivity of reading strategies. The strategy that combines double reading in first participation with single reading in subsequent participations was ruled out due to extended dominance.

Conclusions: From our results, double reading appears not to be a cost-effective strategy in the context of digital mammography. Double reading would eventually be challenged in screening programmes, as single reading might entail important net savings without significantly changing the cancer detection rate. These results are not conclusive and should be confirmed in prospective studies that investigate long-term outcomes like quality adjusted life years (QALYs).

Fig 1. Algorithm followed during a biennial screening round in the programme.

*The reading process included independent double reading followed by consensus and arbitration in case of disagreement.

Fig 2. Decision-tree model used to evaluate the cost-effectiveness of the three reading strategies.

FP = False Positive. FN = False Negative. TN = True Negative.

Fig 3. Cost-effectiveness plane illustrating differences in costs and cancer detection rates between the reading strategies.

DR = Double reading. SR = Single reading. DS = Double reading in prevalent screening and single reading in incident screening. Continuous and dashed lines represent the thresholds if willingness to pay per one additionally detected cancer were €8,342 and €16,684, respectively. Point A represents the expected cancer detection rate at single reading if willingness to pay per single reading were equal to double reading. Point B represents the expected cost at single reading if the cancer detection rate at single reading were equal to that of double reading.

Fig 4. Sensitivity analysis of the incremental cost-effectiveness ratio (ICER) of double reading versus single reading.

DR = Double reading. SR = Single reading. PPV = positive predictive value. SC = Staff costs. ER = early recall was 2.1% in double reading and 1.7% in single reading. *The prevalence of breast cancer was estimated as the number of true positives plus the number of false negatives.