Table 2.
Over-interpretation, under-interpretation, and misclassification rates of single interpretation compared with reference consensus standard and nine second opinion strategies
| Strategies | Rate (%) | Overall (95% CI) | P value* | |||
|---|---|---|---|---|---|---|
| Reference consensus diagnosis | ||||||
| Benign | Atypia | DCIS | Invasive | |||
| Single interpretation and second opinion applied to all cases | ||||||
| Single interpretation: | ||||||
| % requiring 2nd opinion | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Over-interpretation | 12.9 | 17.4 | 2.6 | – | 9.9 (9.0 to 10.8) | |
| Under-interpretation | – | 34.7 | 13.3 | 3.9 | 14.8 (13.8 to 15.9) | |
| Misclassification | 12.9 | 52.2 | 15.9 | 3.9 | 24.7 (23.6 to 25.8) | n/a |
| 1. Second opinion with resolution applied to all cases | ||||||
| % requiring 2nd opinion | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | |
| Requiring 3rd opinion | 19.7 | 55.9 | 21.6 | 3.7 | 29.6 | |
| Over-interpretation | 8.4 | 11.1 | 0.6 | – | 6.0 (4.7 to 7.5) | |
| Under-interpretation | – | 29.9 | 9.3 | 3.5 | 12.1 (10.0 to 14.3) | |
| Misclassification | 8.4 | 40.9 | 9.9 | 3.5 | 18.1 (16.1 to 20.0) | P<0.001 |
| Criterion for obtaining second opinion based on initial diagnosis | ||||||
| 2. Second opinion only for initial interpretations considered atypia or DCIS or invasive: | ||||||
| % requiring 2nd opinion | 12.9 | 65.3 | 93.7 | 99.6 | 61.5 | |
| % requiring 3rd opinion | 10.4 | 36.5 | 17.8 | 3.3 | 19.8 | |
| Over-interpretation | 6.0 | 10.0 | 0.6 | – | 5.0 (3.9 to 6.3) | |
| Under-interpretation | – | 41.8 | 11.4 | 3.9 | 16.4 (14.4 to 18.4) | |
| Misclassification | 6.0 | 51.9 | 12.1 | 3.9 | 21.4 (19.5 to 23.2) | P<0.001 |
| 3. Second opinion only for initial interpretations considered DCIS or invasive: | ||||||
| % requiring 2nd opinion | 3.2 | 17.4 | 86.7 | 99.6 | 42.1 | |
| % requiring 3rd opinion | 2.9 | 13.1 | 12.2 | 3.3 | 8.8 | |
| Over-interpretation | 11.3 | 7.9 | 0.6 | – | 5.9 (4.9 to 7.1) | |
| Under-interpretation | – | 35.9 | 15.2 | 3.9 | 15.8 (13.8 to 17.6) | |
| Misclassification | 11.3 | 43.7 | 15.8 | 3.9 | 21.7 (19.8 to 23.5) | P<0.001 |
| 4. Second opinion only for initial interpretations considered invasive: | ||||||
| % requiring 2nd opinion | 1.0 | 0.4 | 2.6 | 96.1 | 10.4 | |
| % requiring 3rd opinion | 0.8 | 0.3 | 2.4 | 1.9 | 1.2 | |
| Over-interpretation | 12.5 | 17.5 | 0.4 | – | 9.1 (7.7 to 10.6) | |
| Under-interpretation | – | 34.4 | 13.2 | 4.7 | 14.8 (13.0 to 16.5) | |
| Misclassification | 12.5 | 51.9 | 13.6 | 4.7 | 23.9 (22.1 to 25.7) | P=0.25 |
| Second opinion only obtained for cases considered borderline or difficult | ||||||
| 5. Second opinion obtained only for initial interpretations considered borderline: | ||||||
| % requiring 2nd opinion | 19.0 | 45.3 | 21.4 | 3.5 | 26.1 | |
| % requiring 3rd opinion | 7.5 | 25.6 | 9.3 | 0.8 | 12.8 | |
| Over-interpretation | 10.0 | 14.2 | 1.5 | – | 7.7 (6.3 to 9.2) | |
| Under-interpretation | – | 34.6 | 9.9 | 3.8 | 13.8 (11.8 to 15.7) | |
| Misclassification | 10.0 | 48.9 | 11.5 | 3.8 | 21.5 (19.5 to 23.3) | P<0.001 |
| 6. Second opinion obtained only for initial interpretations considered difficult: | ||||||
| % requiring 2nd opinion | 23.2 | 48.2 | 24.8 | 11.1 | 30.0 | |
| % requiring 3rd opinion | 9.0 | 27.3 | 9.8 | 1.5 | 14.0 | |
| Over-interpretation % | 9.2 | 13.8 | 1.6 | – | 7.4 (6.0 to 8.8) | |
| Under-interpretation % | – | 34.3 | 10.1 | 3.3 | 13.7 (11.8 to 15.5) | |
| Misclassification | 9.2 | 48.1 | 11.7 | 3.3 | 21.1 (19.3 to 22.8) | P<0.001 |
| Second opinion only obtained for cases when desired or required by policy, or both | ||||||
| 7. Second opinion only for cases when desired by pathologist: | ||||||
| % requiring 2nd opinion | 26.7 | 55.9 | 30.5 | 15.5 | 35.5 | |
| % requiring 3rd opinion | 10.1 | 31.3 | 11.2 | 1.5 | 16.0 | |
| Over-interpretation | 9.2 | 14.0 | 1.5 | – | 7.4 (5.8 to 9.2) | |
| Under-interpretation | – | 33.7 | 9.9 | 3.6 | 13.4 (11.4 to 15.6) | |
| Misclassification | 9.2 | 47.7 | 11.4 | 3.6 | 20.9 (18.9 to 22.8) | P<0.001 |
| 8. Second opinion only when required by policy: | ||||||
| % requiring 2nd opinion | 33.8 | 40.6 | 55.3 | 59.9 | 44.9 | |
| % requiring 3rd opinion | 7.6 | 23.0 | 10.0 | 2.1 | 12.4 | |
| Over-interpretation % | 10.8 | 13.2 | 1.6 | – | 7.7 (6.3 to 9.1) | |
| Under-interpretation % | – | 33.9 | 12.1 | 4.0 | 14.2 (12.3 to 16.1) | |
| Misclassification | 10.8 | 47.1 | 13.7 | 4.0 | 21.9 (20.0 to 23.7) | P<0.001 |
| 9. Second opinion only when desired or required by policy: | ||||||
| % requiring 2nd opinion | 54.0 | 80.4 | 75.5 | 69.8 | 70.0 | |
| % requiring 3rd opinion | 14.9 | 45.3 | 18.0 | 3.0 | 23.8 | |
| Over-interpretation % | 8.1 | 11.4 | 0.9 | – | 6.1 (4.8 to 7.5) | |
| Under-interpretation % | – | 32.8 | 9.5 | 3.7 | 13.1 (11.1 to 15.2) | |
| Misclassification | 8.1 | 44.3 | 10.3 | 3.7 | 19.2 (17.3 to 21.0) | P<0.001 |
*Based on Wald test for difference in overall misclassification rates between second opinion strategy and single pathologist interpretation. Test statistic uses bootstrap standard error of difference in rates.