Table 4

Per patient sensitivity, specificity, positive and negative predictive values for CT colonography (CTC) per lesion size category

Both FOBTI-FOBT 50 ng/mlI-FOBT 100 ng/mlG-FOBT
%Ratio (95% CI)%Ratio (95% CI)%Ratio (95% CI)%Ratio (95% CI)
Lesions ⩾10 mm*
Sensitivity82116/142 (74 to 89)8088/110 (72 to 88)8169/85 (74 to 89)8828/32 (81 to 94)
Specificity86138/160 (80 to 93)86119/138 (79 to 93)8858/66 (81 to 94)8619/22 (80 to 93)
PPV84116/138 (77 to 91)8288/107 (75 to 90)9069/77 (84 to 96)9028/31 (85 to 96)
NPV84138/164 (77 to 91)84119/141 (77 to 92)7858/74 (70 to 86)8319/23 (75 to 90)
Lesions ⩾6 mm†
Sensitivity91192/211 (85 to 91)90157/174 (84 to 96)90100/111 (84 to 96)9434/36 (90 to 99)
Specificity6963/91 (60 to 89)7253/74 (63 to 80)6827/40 (57 to 77)5610/18 (46 to 65)
PPV87119/220 (80 to 93)88157/178 (82 to 95)88100/113 (82 to 95)8134/42 (73 to 89)
NPV7763/82 (69 to 85)7653/70 (67 to 84)7127/38 (62 to 80)8310/12 (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.