The yield and patient factors associated with CT colonography C-RADS results in a non-screening patient population

To determine the proportion of diagnostic computed tomography colonography (CTC) Reporting and Data System (C-RADS) categories in a non-screening population, and which patient factors are associated with a positive CTC (C2–4), a non-diagnostic CTC (C0), and potentially relevant extracolonic findings (ECF, E3–4).

Diagnostic CTCs performed at a single academic center from 2017 to 2018 were retrospectively reviewed. For each examination, the indications, age, sex, admission status, and C-RADS categories were recorded. Multivariate logistic regression was performed of patient demographic factors and clinical indications, with adjusted odds ratios (OR) and 95% confidence intervals.

1373 CTCs were included. The mean age was 66.4 ± 13 years (range 24–97). There were 782 women and 75 inpatients. The number of CTCs reported as C0–C4 were 194/1373 (14.1%), 970/1373 (70.6%), 77/1373 (5.6%), 86/1373 (6.3%), and 46/1373 (3.4%), respectively, and 134/1373 (9.8%), 960/1373 (69.9%), 173/1373 (12.6%), and 106/1373 (7.7%) CTCs were reported as E1–4, respectively. Factors that demonstrated the strongest associations were as follows: with C2–4, age groups 50–79 (OR 2.8, 95% confidence interval 1.4–6.1), 80–89 (6.2, 2.9–14.5) and ≥ 90 (7.6, 2.0–29.1), and inpatients (3.4, 1.8–6.4); with C0, age groups 50–79 (5.9, 2.2–24.4), 80–89 (9.8, 3.4–41.8), and ≥ 90 (22.5, 5.8–113.0), incomplete colonoscopy (3.2, 2.0–5.1) and melena or gastrointestinal bleeding (4.1, 1.8–9.4); and with E3–4, age groups 50–79 (1.6, 1.0–2.9), 80–89 (2.0, 1.1–3.9), and ≥ 90 (3.2, 1.2–8.8), and inpatients (2.3, 1.3–3.9).

Older age is increasingly associated with a positive test, a non-diagnostic test and potentially relevant ECF. Inpatients are also associated with positive tests and E3–4 findings. Symptoms are not strongly associated with a positive CTC.