Adenomas and Sessile Serrated Lesions in 45- to 49-Year-Old Individuals Undergoing Colonoscopy: A Systematic Review and Meta-Analysis

Colorectal cancer (CRC) screening is now recommended at the age of 45 years in the United States. However, information regarding the adenomas detection rate (ADR) and sessile serrated lesions (SSLs) in 45- to 49-year-old individuals is limited. In addition, the impact of lowering the screening age to 45 years on the ADR and the detection rate of SSLs is not well elucidated. This systematic review and meta-analysis aims to report the overall ADR and SSL detection rate in 45- to 49-year-old individuals undergoing colonoscopy. We searched MEDLINE, EMBASE, SCOPUS, Web of Science, ClinicalTrials.gov , and the Cochrane database from inception through October 2022 to identify studies reporting on ADR and SSL detection rates in 45- to 49-year-old individuals undergoing colonoscopies for all indications. This approach acknowledges the possibility of including individuals undergoing diagnostic colonoscopies or those with increased risk factors for CRC. We also conducted a separate analysis examining ADR in average-risk individuals undergoing screening colonoscopy. The pooled rates with their corresponding 95% confidence intervals (CIs) were generated using the fixed-effects model. I2 was used to adjudicate heterogeneity. Sixteen studies met the inclusion criteria. All studies were retrospective except one; 3 had data from national/local registries. There were 41,709 adenomas detected across 150,436 colonoscopies. The pooled overall ADR was 23.1% (95% CI 19.7%-27.0%, I2 = 98.6%). The pooled ADR in individuals with average risk of CRC from 7 studies was 28.2% (95% CI 24.6%-32.0%, I2 = 96.5%). The pooled overall SSL detection rate from 6 studies was 6.3% (95% CI 3.8%-10.5%, I2 = 97%). The included studies were heterogeneous because of differences in the inclusion and exclusion criteria and patient population. In 45- to 49-year-old individuals undergoing a colonoscopy for any indication, the ADR and SSL detection rates were 23.1% and 6.3%, respectively. We conclude that these outcomes in 45- to 49-year-olds are comparable with individuals aged 50-54 years.