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CLINICAL CONCLUSIONS

CLINICAL CONCLUSIONS. Granting the statistical significance of a gain in A z of 0.02 (95% CI: 0.01, 0.04), what is the clinical significance ? . Clinical Utility ... CAD intended to reduce missed nodules; i.e., intended to increase user’s SENSITIVITY .

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CLINICAL CONCLUSIONS

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  1. CLINICAL CONCLUSIONS Sacks

  2. Granting the statistical significanceof a gain in Azof 0.02(95% CI: 0.01, 0.04), what is the clinical significance? Sacks

  3. Clinical Utility • ... CAD intended to reduce missed nodules; i.e., intended to increase user’s SENSITIVITY ... Sacks

  4. Gain of 0.02 in AZ understates relative gain in sensitivity. Why? Sacks

  5. When CAD is used according to instruction to retain all judgments of actionability even if unmarked by CAD... Sacks

  6. ... user always maintains or increases sensitivity, and always maintains or increases FPF, as well. Sacks

  7. ROC 1 ΔFPR Aided FNRU ΔSe =ΔFNR Unaided SeU Chance line (guessing) TPR 0 1 0 FPR Sacks

  8. ROC 1 Loss of Se only possible if instruction not followed Aided Realistic Unaided Chance line (guessing) TPR 0 1 0 FPR Sacks

  9. So any statistically significant improvement in Az means an even greater relative gain in Se, and one achieved without falling to a lower ROC curve. Sacks

  10. The real question for judging the safety and effectiveness of a CAD is... Sacks

  11. Can we infer from improved average user performance (Az) in a clinical study ... Sacks

  12. ... that the average user will improve performance (Az) with CAD in clinical practice ... Sacks

  13. ... i.e., improve over her/his performance (Az) in current clinical practice? Sacks

  14. To put it another way, is the unaided reading in a clinical study a good surrogate for current (CAD-less) clinical practice? Sacks

  15. Aided reading Az Unaided reading CAD-less reading Clinical study Current clinical practice Sacks

  16. For example, in actual clinical practice with CAD, the unaided Az could be lowered by failure to read first as one would normally read (i.e., with adequate vigilance). Sacks

  17. If this were to happen, then the aided Az could also be lower than current (CAD-less) practice. Sacks

  18. Az Aided reading CAD-less reading Unaided reading Clinical study Current clinical practice Sacks

  19. What would be the implications of such lowering of vigilance for judging the safety and effectiveness of the CAD? Sacks

  20. Can labeling help prevent this? Sacks

  21. LABELING ISSUE • Two rules, if followed by CAD user in future clinical practice, will help prevent missing more nodules than former reading without CAD: Sacks

  22. Always read unaided first, and as carefully as if you had no CAD. • (This would help keep Az of aided reading higher than Az of current CAD-less reading.) Sacks

  23. Never back off from unaided judgment of actionability of a nodule if CAD fails to mark it. • (This would prevent sensitivity from falling below that of current CAD-less sensitivity. I.e., it would prevent missing more, rather than fewer, nodules.) Sacks

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