4. Subgroup analyses according to type of contrast enhancement and radiation dose.
Subgroups by enhancement and dose |
Number of analyses (studies)a |
Summary estimates with 95% CI | Absolute differences in summary estimates with 95% CI |
||||
Sensitivity | Specificity | Positive likelihood ratio |
Negative likelihood ratio |
Sensitivity | Specificity | ||
Unenhanced | 19 (19) | 0.91 (0.87‐0.93) | 0.94 (0.90–0.96) | 15 (9–24) | 0.10 (0.07–0.14) | – | – |
IV contrast | 18 (17) | 0.96 (0.92–0.98) |
0.93 (0.90–0.95) | 14 (9–20) | 0.04 (0.02–0.09) | 0.04b (0.00–0.09) | ‐0.01b (‐0.04–0.03) |
IV and oral contrast | 15 (15) | 0.96 (0.93–0.98 | 0.94 (0.92–0.96) | 17 (12–26) | 0.04 (0.02–0.07) |
0.05b (0.01–0.09) |
0.01b (‐0.03–0.04) |
Rectal contrast | 9 (9) | 0.97 (0.93–0.99) | 0.95 (0.90–0.98) | 21 (9–51) | 0.04 (0.02–0.08) | 0.05b (0.01–0.09) |
0.01b (‐0.03–0.06) |
Oral contrast | 7 (7) | 0.89 (0.81–0.94) |
0.94 (0.90–0.97) |
16 (9–29) |
0.11 (0.06–0.21) |
‐0.01b (‐0.08–0.6) |
0.01b (‐0.03–0.05) |
Standard dose | 67 (64) | 0.95 (0.93–0.96) |
0.94 (0.92–0.95) |
15.6 (12.3–19.7) | 0.05 (0.04–0.07) | – | – |
Low dose | 8 (7) | 0.94 (0.90–0.97) |
0.94 (0.91–0.96) |
16 (10–24) |
0.06 (0.03–0.11) | 0.00c (‐0.04–0.05) | 0.00c (‐0.04–0.03) |
Overall | 71 | 0.95 (0.93–0.96) | 0.94 (0.92–0.95) | 15 (12–19 ) | 0.05 (0.04–0.07) | ‐ | ‐ |
CI: confidence interval. IV: intravenous. aRandomised and paired studies provided two or more analyses. bAbsolute difference compared to unenhanced CT. cAbsolute difference compared to standard‐dose CT.