Introduction
The high diagnostic accuracy of colon capsule endoscopy (CCE) for colorectal polyps makes it a valid alternative in colorectal screening compared to conventional colonoscopy [1, 2]. To achieve an acceptable adenoma detection rate (ADR) by colonoscopy the scope withdrawal time should be > 6 minutes (min) [3]. No guideline currently exists for the optimal colon transit time (CTT) in CCE. We aimed to investigate the impact of CCT on polyp detection rate (PDR) to establish a minimum CCT for an acceptable PDR.
Aims & Methods
Between August 2020 and December 2022, the trial CareForColon2015 was conducted in Denmark [4,5]. Complete CCE investigation was defined a study with visualization of the hemorrhoidal plexus or excreted capsule within battery lifetime and bowel preparation rated fair or better on the Leighton-Rex scale for all colonic segments. PDR was defined as number of CCEs in which at least one polyp was detected, divided by the total number of CCEs. Additionally, we calculated two PDRs limited to polyps > 5 and > 9 millimeter (mm), respectively. Statistical analyses were performed in Stata/BE 17.0 (StataCorp, Texas, USA). Logistic regression models adjusted for age, sex and bowel preparation were used to estimate odds ratios (OR) for polyp detection based on CTT as a categorical variable.
Results
Two thousand and thirty had CCE; 616 were excluded due to incomplete investigation (30.3%). For the complete CCEs, the total PDR was 79.4%. PDR was 68.8% for polyps > 5 mm and 46.5% for polyps > 9 mm. CTT > 60 min (n = 1,009) was set as reference in the analyses of PDR stratified by CTT ≤ 15 min (n = 74), CTT 16-30 min (n = 126) and CTT 31-60 min (n = 205). The OR of polyp detection was significantly lower for CTT ≤ 15 min (OR 0.334, p < 0.001) and CTT 31-60 min (OR 0.663, p = 0.013) (Table 1). Regarding PDR for polyps > 5 mm, the OR was significantly lower for investigations ≤ 15 min (OR 0.466, p = 0.003) and 31-60 min (OR 0.695, p = 0.027) (Table 1). No significant differences for PDR concerning polyps > 9 mm and CTT were observed (Table 1).
Table 1 Calculated odds ratio (OR), 95 % confidence interval, p value and forest plot for PDR overall, PDR > 5 mm and PDR > 9 mm stratified for colonic transit time (CTT). For all calculations, CTT > 60 minutes was set as baseline and OR are adjusted for sex and age.
| CTT (min) | n | OR | 95% - CI | p-value |
| PDR | 1-15 | 74 | 0.334 | 0.199 – 0.560 | <0.001 |
| 16-30 | 126 | 0.796 | 0.502 – 1.261 | 0.331 |
| 31-60 | 205 | 0.633 | 0.442 – 0.906 | 0.013 |
PDR
polyps
> 5 mm | 1-15 | 74 | 0.466 | 0.284 – 0.766 | 0.003 |
| 16-30 | 126 | 1.016 | 0.669 – 1.545 | 0.940 |
| 31-60 | 205 | 0.695 | 0.503 – 0.960 | 0.027 |
PDR
polyps
> 9 mm | 1-15 | 74 | 0.790 | 0.487 – 1.282 | 0.422 |
| 16-30 | 126 | 1.307 | 0.896 – 1.909 | 0.165 |
| 31-60 | 205 | 0.747 | 0.548 – 1.012 | 0.065 |
*
Aberrations: CTT; Colonic transit time,
OR; Odds ratio,
PDR; Polyp detection rate
Conclusion
Until now, expert opinion is used in evaluation of CCE investigation validity; Rex et al. suggests CTT < 40 min combined with poor preparation as a technically inadequate investigation for polyps [6]. Also, Pickhardt et al. have demonstrated the malignant potential of polyps > 9 mm to be significantly higher than of diminutive polyps [7], suggesting the impact of missed polyps ≤ 9 mm to be low. Thus, our results suggests CTT to have minor clinical impact on patient pathway in colorectal screening CCE although a CTT ≤ 60 min is significantly correlated with lower PDR compared to CTT > 60 min.
References
1. Kjølhede T, Ølholm AM, Kaalby L, et al. Diagnostic accuracy of capsule endoscopy compared with colonoscopy for polyp detection: systematic review and meta-analyses. Endoscopy. 2021;53(07):713-21.
2. Sulbaran M, Bustamante-Lopez L, Bernardo W, et al. Systematic review and meta-analysis of colon capsule endoscopy accuracy for colorectal cancer screening. An alternative during the Covid-19 pandemic? J Med Screen. 2022;29(3):148-55.
3. Barclay RL, Vicari JJ, Doughty AS, et al. Colonoscopic Withdrawal Times and Adenoma Detection during Screening Colonoscopy. New England Journal of Medicine. 2006;355(24):2533-41.
4. Kaalby L, Deding U, Kobaek-Larsen M, et al. Colon capsule endoscopy in colorectal cancer screening: a randomised controlled trial. BMJ Open Gastroenterol. 2020;7(1).
5. Deding U, Bjorsum-Meyer T, Kaalby L, et al. Colon capsule endoscopy in colorectal cancer screening: Interim analyses of randomized controlled trial CareForColon2015. Endosc Int Open. 2021;9(11):E1712-E9.
6. Rex DK, Adler SN, Aisenberg J, et al. Accuracy of Capsule Colonoscopy in Detecting Colorectal Polyps in a Screening Population. Gastroenterology. 2015;148(5):948-57.e2.
7. Pickhardt, P. J., Hassan, C., Laghi, et al. Small and diminutive polyps detected at screening CT colonography: a decision analysis for referral to colonoscopy. AJR. American journal of roentgenology. 2008; 190(1), 136–144.
Disclosure
A.K.: Co-founder and shareholder of A.J.M. Medicaps; co-director and shareholder of iCERV Ltd.; consultancy fees (Jinshan Ltd.); travel support (Jinshan, Aquilant, and Dr Falk Pharma); research support (grant) from ESGE/Given Imaging Ltd. And (material) IntroMedic/SynMed; honoraria (Dr Falk Pharma UK, Ferring, Jinshan, Medtronic). Member of Advisory board meetings (Dr Falk Pharma UK, Tillots, ANKON).