Adenoma detection rate of screening colonoscopy among age 40–75 years: Implications for lowering the age for colorectal cancer screening

Incidence of early‐onset colorectal cancer is on the rise, prompting updated international guidelines recommending screening for average‐risk individuals starting at age 45. Adenoma detection rate (ADR) serves as a crucial quality indicator for colonoscopy (CFS), with a current benchmark of 25% for screening CFS starting at age 50. However, the impact of lowering the screening age on ADR remains uncertain. This study aimed to assess the ADR in average‐risk individuals who undergo screening colonoscopy at an age older than 40. Participants who underwent a complete colonoscopy for health examination at a medical center between January 2014 and February 2020 were enrolled in this study. We excluded colonoscopies performed on individuals younger than 40 years of age or older than 75 years of age, as well as those conducted for surveillance purposes. ADR was defined as the percentage of colonoscopies with at least one colorectal adenoma detected. We calculated the ADR for different age groups, including 40–44, 45–49, 50–54, and 55–75, to understand the age‐specific ADR of screening colonoscopy. Additionally, we evaluated the ADR among participants who started screening colonoscopy at ages ≥40, ≥45, and ≥50 to understand the impact of starting age on ADR. A p value <.05, determined by the chi‐square test, was considered significant. Among the 33 073 CFS completed during the study period, 5852 CFS examined in patients aged younger than 40 years, 344 CFS examined in patients aged older than 75, and 6881 CFS with surveillance indication were excluded, leaving 19 996 CFS enrolled for analysis. The mean age of the participants was 53, with 57% being male and 43% being female. The ADR for the age groups of 40–44, 45–49, 50–54, and 55–75 were 28.0% (1058/3778), 31.8% (1191/3741), 35.6% (1387/3891), and 44.2% (3794/8586), respectively, with a statistically significant difference (p < .01). The ADR for age ≥40, ≥45, and ≥50 were 37.2% (7430/19996), 40.1% (6372/15874), and 41.5% (5181/12477), respectively, with a statistically significant difference (p < .01). The findings of our study indicate that there are notable differences in ADR among various age groups. Lowering the screening age might result in a decrease in the overall ADR. However, our results suggest that even if CRC screening begins at age 40 or 45, the current benchmark of 25% ADR for screening colonoscopy may still be maintained. These findings provide valuable insights into the age‐ and gender‐specific prevalence of adenomas in colonoscopy screening and can be used to inform future screening guidelines and recommendations.