Table 2. Per-participant accuracy of gastroenterologists and radiologists in detecting cancers or adenomas on CTCa.
| Performance by participant |
Cancer or adenoma ≥6 mm |
Cancer or adenoma ≥10 mm |
||
|---|---|---|---|---|
| GI | RAD | GI | RAD | |
| True-positive results, no. | 278 | 265 | 162 | 160 |
| False-negative results, no. | 31 | 44 | 13 | 15 |
| True-negative results, no. | 798 | 773 | 978 | 971 |
| False-positive results, no. | 57 | 82 | 11 | 18 |
| C0 (CTC image not available) | 13 | 13 | 13 | 13 |
| Sensitivity (95% CI) | 0.90 (0.86–0.93) | 0.86 (0.81–0.89) | 0.93 (0.88–0.96) | 0.91 (0.86–0.95) |
| P value | 0.024 | 0.453 | ||
| Participants with lesions, no. | 309 | 309 | 175 | 175 |
| Specificity (95% CI) | 0.93 (0.91–0.95) | 0.90 (0.88–0.92) | 0.99 (0.98–0.99) | 0.98 (0.97–0.99) |
| P value | 0.002 | 0.077 | ||
| Participants without lesions, no. | 855 | 855 | 989 | 989 |
| Positive predictive value (95% CI) | 0.83 (0.79–0.87) | 0.76 (0.72–0.81) | 0.94 (0.89–0.97) | 0.90 (0.84–0.94) |
| P value | 0.003 | 0.086 | ||
| Positive test results, no. | 335 | 347 | 173 | 178 |
| Negative predictive value (95% CI) | 0.96 (0.95–0.97) | 0.95 (0.93–0.96) | 0.99 (0.98–0.99) | 0.98 (0.98–0.99) |
| P value | 0.024 | 0.45 | ||
| Negative test results, no. | 829 | 817 | 991 | 986 |
| Positive likelihood ratio (95% CI) | 13.50 (10.47–17.39) | 8.94 (7.24–11.04) | 83.23 (46.18–150.02) | 50.24 (31.72–79.58) |
| Negative likelihood ratio (95% CI) | 0.11 (0.08–0.15) | 0.16 (0.12–0.21) | 0.08 (0.05–0.13) | 0.09 (0.05–0.14) |
| Area under the ROC curve (95% CI) | 0.93 (0.91–0.95) | 0.91 (0.88–0.93) | 0.96 (0.93–0.97) | 0.95 (0.92–0.97) |
| P value | 0.029 | 0.499 | ||
CI, confidence interval; CTC, computed tomographic colonography; GI, gastroenterologist; RAD, radiologist; ROC, receiver-operating characteristic.
Values of RAD for detection of lesions on CTC were averaged among radiologists, and values of GI for detection of lesions were averaged among gastroenterologists. Sensitivity indicates the proportion of participants who had lesions (of the specified size) detected on colonoscopy that were also detected on CTC. Specificity indicates the proportion of participants who had no lesions detected on colonoscopy or on CTC. Positive predictive value indicates the proportion of participants with CTC findings (of the specified size) that were also detected on colonoscopy. Negative predictive value indicates the proportion of participants with no lesions of the specified size detected on CTC who also had no lesions detected on colonoscopy. The ROC curve plots sensitivity vs. the false-positive rate, and the area under the ROC curve indicates the accuracy of CTC.