Introduction
Despite the rising global incidence of colorectal cancer (CRC) and increasing pressure on endoscopy services, colon capsule endoscopy (CCE) has seen limited clinical uptake, primarily due to a lack of trust in its diagnostic accuracy. Although multiple systematic reviews and meta-analyses have reported reasonable polyp detection rates, scepticism persists. This meta-review and meta-meta-analysis aim to synthesise evidence on CCE’s diagnostic accuracy in polyp and CRC detection, using CT colonography or colonoscopy as the reference standard.
Aims & Methods
We conducted a systematic search of EMBASE, MEDLINE, and PubMed for systematic reviews, with or without meta-analyses, evaluating the diagnostic accuracy of CCE in detecting polyps and CRC. A qualitative thematic review and meta-meta-analysis were conducted following PRISMA guidelines. A bivariate generalised linear mixed model (GLMM) with random effects was used for pooled diagnostic accuracy estimates, and meta-regression was performed using restricted maximum likelihood (REML) estimation.
Results
Nine systematic reviews (8 with meta-analyses) were included, comprising 3472 participants in 28 unique primary studies after removing duplicates. A total of 82 studies were included across nine systematic reviews, but only 28 were unique primary studies. The corrected covered area (CCA) was 100%, indicating a high overlap among the systematic reviews. A subsequent meta-analysis of all 28 unique primary studies showed a pooled per-patient diagnostic accuracy for detecting polyps of any size with a sensitivity of 0.79 (95% CI: 0.69–0.86), specificity: 0.77 (95% CI: 0.71–0.82) and AUC: 0.81 (95% CI: 0.47–0.96). For polyps ≥6mm, the sensitivity, specificity, and AUC were 0.80, 0.87, and 0.81, respectively. Detection of polyps ≥10mm showed a sensitivity of 0.88, specificity of 0.95, and AUC of 0.95. The second-generation CCE (CCE2) demonstrated improved accuracy in any size polyps: Sensitivity 0.90 (95% CI: 0.79–0.96), Specificity: 0.81 (95% CI: 0.70–0.89) and AUC: 0.82 (95% CI: 0.46–0.96). For polyps ≥6mm, CCE2 achieved AUC 0.92, and for polyps ≥10mm, AUC 0.94. CCE2 subgroup analysis demonstrated a high sensitivity of 0.90 (95% CI: 0.79-0.96) for any polyp size and 0.87 (95% CI:0.82-0.91) for polyps ≥6mm, with both results exhibiting low heterogeneity (P >0.05, I² <25%). The pooled CRC detection sensitivity was 0.96 (95% CI: 0.73–1.00) after excluding missed cancers due to capsule battery exhaustion before excretion.
| Overall and subgroup analysis | Pooled Sensitivity (95%CI) | Pooled Specificity (95%CI) | Pooled PLR
(95%CI) | Pooled NLR (95%CI) | Pooled DOR
(95%CI) | SROC-AUC
(95%CI) |
Any Polyp size
(n=14) | 0.79 (0.69-0.86)
| 0.77 (0.71-0.82) | 3.36 (2.54-4.19) | 0.28 (0.17-0.38) | 12.21 (5.39-19.03) | 0.81 (0.47-0.96) |
Polyp size ≥6mm
(n=18) | 0.80(0.72-0.86) | 0.87 (0.82-0.91) | 6.07 (4.03-8.11) | 0.22 (0.15-0.30) | 27.04 (11.94-42.13) | 0.81 (0.48-0.95) |
Polyp size ≥10mm
(n=14) | 0.88 (0.79-0.94) | 0.95 (0.90-0.97) | 16.80 (5.38-28.21) | 0.12 (0.05-0.20) | 133.16 (3.67-262.64) | 0.95 (0.72-0.99) |
CCE1 capsule
Any polyp size
(n=8) | 0.68 (0.61-0.74) | 0.74 (0.68-0.79) | 2.67 (2.07-3.26) | 0.43 (0.34-0.52) | 6.18 (3.59-8.78) | 0.71 (0.71-0.88) |
CCE2 capsule
Any polyp size (n=6) | 0.90 (0.79-0.96) | 0.81 (0.70-0.89) | 4.81 (3.04-6.58) | 0.11 (0.03-0.19) | 44.47 (14.94-74.01) | 0.82 (0.46-0.96) |
CCE1 capsule
size ≥6mm
(n=9) | 0.69 (0.56-0.79) | 0.83 (0.76-0.89) | 3.78 (2.69-4.86) | 0.40 (0.28-0.52) | 9.45 (5.17-13.73) | 0.73 (0.46-0.90) |
CCE2 capsule
size ≥6mm
(n=9) | 0.88 (0.85-0.90) | 0.92 (0.88-0.94) | 9.03 (4.40-13.67) | 0.13 (0.09 – 0.17) | 68.32 (34.85 – 101.79) | 0.92 (0.85-0.96) |
CCE1 capsule
size ≥10mm
(n=3) | 0.90 (0.85-0.93) | 0.88 (0.83-0.91) | 7.30 (4.90-9.69) | 0.11 (0.061-0.16) | 65.75 (30.96-100.55) | NA- Insufficient number of studies |
CCE2 capsule
size ≥10mm
(n=11) | 0.86 (0.75-0.93) | 0.96 (0.94-0.97) | 8.74 (5.16-12.31) | 0.13 (0.056-0.21) | 66.45 (18.34-114.56) | 0.94 (0.71-0.99) |
Table 1. Overall and subgroup analysis for diagnostic accuracy of CCE in Polyp detection using Generalised Linear Mixed Model (GLMM).
Conclusion
This analysis confirms CCE2's high diagnostic accuracy for polyp and colorectal cancer detection. While technical challenges persist, CCE2 shows promise as a complementary diagnostic tool to help address increasing endoscopy service demands.
References
Rokkas T, et al. A meta-analysis evaluating the accuracy of colon capsule endoscopy in detecting colon polyps. Gastrointest Endosc. 2010;71(4):792-8.
Spada C, et al. Meta-analysis shows colon capsule endoscopy is effective in detecting colorectal polyps. Clin Gastroenterol Hepatol. 2010;8(6):516-22.
Spada C, et al. Accuracy of First- and Second-Generation Colon Capsules in Endoscopic Detection of Colorectal Polyps: A Systematic Review and Meta-analysis. Clin Gastroenterol Hepatol. 2016;14(11):1533-43 e8.
Vuik FER, et al. Colon capsule endoscopy in colorectal cancer screening: a systematic review. Endoscopy. 2021;53(8):815-24.
Alihosseini S, et al. Second-generation colon capsule endoscopy for detection of colorectal polyps: A meta-analysis. Med J Islam Repub Iran. 2020;34:81.
Kjolhede T, et al. Diagnostic accuracy of capsule endoscopy compared with colonoscopy for polyp detection: systematic review and meta-analyses. Endoscopy. 2021;53(7):713-21.
Ali H, et al. Diagnostic Accuracy for Per-Patient Polyp Detection of Second-Generation Capsule Endoscopy Compared to Colonoscopy: A Meta-Analysis of Multicenter Studies. Cureus. 2021;13(8):e17560.
Mollers T, et al. Second-generation colon capsule endoscopy for detection of colorectal polyps: Systematic review and meta-analysis of clinical trials. Endosc Int Open. 2021;9(4):E562-E71.
Sulbaran M, 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.
Disclosure
No conflict of interest
