Forty seven studies, with a total of 10,546 participants (range 20 to 2,600), were included in the review. The results of QUADAS assessment were reported in full.
Sensitivity: The pooled estimate of the per polyp sensitivity of CTC was 66% (95% CI 64% to 68%), based on 37 studies, with significant between-study heterogeneity. The pooled estimate of the per patient sensitivity was 69% (95% CI 66% to 72%), based on 16 studies with significant between-study heterogeneity. Both per patient and per polyp sensitivity increased with polyp size. Subgroup analyses indicated that the per patient sensitivity of CTC was significantly higher where: sodium phosphate was for bowel preparation versus not used; faecal tagging was used versus not used; where 3D imaging was always used versus only used for confirmation; where higher radiation doses (>100mA) were used; and in average risk compared to high risk populations.
Specificity: The pooled estimate for CTC specificity was 83% (95% CI 81% to 84%), based on an un-reported number of studies with significant between-study heterogeneity. The specificity estimate increased with increasing polyp size. No other subgroup analyses were reported for specificity.
Likelihood ratios: Pooled positive and negative likelihood ratios were 2.9 (95% CI 1.8 to 4.0) and 0.38 (95% CI 0.27 to 0.53).