Linked color imaging versus conventional white-light colonoscopy for the detection of colorectal polyps.

Rationale: Early detection of colorectal polyps using colonoscopy is important for preventing post-colonoscopy colorectal cancer (PCCRC) because a 1% increase in adenoma detection rate (ADR) is associated with a 3% decrease in PCCRC incidence. Linked color imaging (LCI) enhances color contrast compared to white-light imaging (WLI), potentially improving ADR. Existing reviews provide promising yet inconclusive findings on LCI's benefits, highlighting the need for this systematic review.

Objectives: To assess the benefits and harms of LCI compared to WLI colonoscopy in detecting colorectal polyps in people requiring colonoscopy for screening, symptoms, or surveillance.

Search methods: We searched CENTRAL, MEDLINE, Embase, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform from 2014 to 30 May 2025. We screened the reference lists of relevant review articles and current treatment guidelines to identify additional studies. We contacted the study authors in case of any missing data.

Eligibility criteria: We included randomized controlled trials (RCTs) comparing LCI and WLI. We excluded non-RCTs. We included adults 18 years of age and older who required colonoscopy for screening, symptom assessment, and surveillance in any healthcare setting.

Outcomes: The critical outcomes were ADR during the study period, proportion of participants with PCCRC at next scheduled follow-up colonoscopy, and proportion of adverse events requiring medical treatment during the study period. Important outcomes were polyp detection rate and sessile serrated lesion detection rate during the study period, numbers of adenomas, polyps, and flat polyps per participant at the end of a single colonoscopy, and all adverse events during the study period.

Risk of bias: Two authors assessed study risk of bias using version two of the Cochrane tool for assessing risk of bias in randomized trials (RoB 2).

Synthesis methods: We synthesized results for each outcome using random-effects meta-analysis, calculating risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, each with 95% confidence intervals (CIs), using Review Manager. Where meta-analysis was not possible due to data heterogeneity or insufficient reporting, we applied the Synthesis Without Meta-analysis (SWiM) approach. We used GRADE to assess the certainty of the evidence.

Included studies: We included 16 trials, with 12,836 participants. Nine trials focused on screening/surveillance and seven on screening and symptomatic patients. We judged six trials as being at low risk of bias overall.

Synthesis of results: Critical outcomes LCI slightly increases ADR compared to WLI (RR 1.18, 95% CI 1.10 to 1.28; 15 RCTs, 12,877 participants; high-certainty evidence). No study reported the proportion of participants with PCCRC. There were no adverse events requiring medical treatment (6 RCTs, 5240 participants; moderate-certainty evidence). Important outcomes LCI slightly increases polyp detection rate (RR 1.14, 95% CI 1.09 to 1.19; 12 RCTs, 11,243 participants; high-certainty evidence), and likely increases sessile serrated lesion detection rate (RR 1.61, 95% CI 1.31 to 1.98; 7 RCTs, 8605 participants; moderate-certainty evidence), and the number of adenomas per participant (MD 0.18, 95% CI 0.03 to 0.32; 11 RCTs, 10,833 participants; moderate-certainty evidence). A key limitation of the evidence was imprecision for sessile serrated lesion detection and number of adenomas per participant due to small sample sizes. Similarly, zero events were reported for adverse events requiring medical treatment, limiting precision despite adequate sample sizes. Additionally, no study reported the proportion of participants with PCCRC, further restricting our conclusions.

Authors' conclusions: We found high-certainty evidence that LCI slightly increases ADR and moderate-certainty evidence that LCI likely results in little to no difference in the proportion of adverse events requiring medical treatment; data on the proportion of participants with PCCRC are unavailable. We also found high-certainty evidence that LCI slightly improves polyp detection rate and moderate-certainty evidence that LCI likely increases sessile serrated lesion detection rate and the number of adenomas and polyps per participant. Further studies should focus on measuring clinically significant outcomes, such as the proportion of participants with PCCRC.

Funding: This study had no dedicated funding.

Registration: Protocol available via DOI 10.1002/14651858.CD015476.