Table 4.
Per patient sensitivity, specificity, positive and negative predictive values for CT colonography (CTC) per lesion size category
| Both FOBT | I-FOBT 50 ng/ml | I-FOBT 100 ng/ml | G-FOBT | |||||
| % | Ratio (95% CI) | % | Ratio (95% CI) | % | Ratio (95% CI) | % | Ratio (95% CI) | |
| Lesions ⩾10 mm* | ||||||||
| Sensitivity | 82 | 116/142 (74 to 89) | 80 | 88/110 (72 to 88) | 81 | 69/85 (74 to 89) | 88 | 28/32 (81 to 94) |
| Specificity | 86 | 138/160 (80 to 93) | 86 | 119/138 (79 to 93) | 88 | 58/66 (81 to 94) | 86 | 19/22 (80 to 93) |
| PPV | 84 | 116/138 (77 to 91) | 82 | 88/107 (75 to 90) | 90 | 69/77 (84 to 96) | 90 | 28/31 (85 to 96) |
| NPV | 84 | 138/164 (77 to 91) | 84 | 119/141 (77 to 92) | 78 | 58/74 (70 to 86) | 83 | 19/23 (75 to 90) |
| Lesions ⩾6 mm† | ||||||||
| Sensitivity | 91 | 192/211 (85 to 91) | 90 | 157/174 (84 to 96) | 90 | 100/111 (84 to 96) | 94 | 34/36 (90 to 99) |
| Specificity | 69 | 63/91 (60 to 89) | 72 | 53/74 (63 to 80) | 68 | 27/40 (57 to 77) | 56 | 10/18 (46 to 65) |
| PPV | 87 | 119/220 (80 to 93) | 88 | 157/178 (82 to 95) | 88 | 100/113 (82 to 95) | 81 | 34/42 (73 to 89) |
| NPV | 77 | 63/82 (69 to 85) | 76 | 53/70 (67 to 84) | 71 | 27/38 (62 to 80) | 83 | 10/12 (76 to 91) |
*Detection of lesions ⩾10 mm at colonoscopy using a CTC size cut-off of ⩾10 mm. †Detection of lesions ⩾6 mm at colonoscopy using a CTC size cut-off of ⩾6 mm.
FOBT, faecal occult blood test; G-FOBT, guaiac FOBT; I-FOBT, immunochemical FOBT; NPV, negative predictive value; PPV, positive predictive value.