Prevalence and Variable Detection of Sessile Serrated Polyps in Young Adults Undergoing Index Diagnostic Colonoscopy

Abstract

Introduction: Population-based CRC screening programs are typically focused on patients ≥50 years of age. There is therefore limited data on the prevalence and variable detection of SSPs in younger patients and even less around SSP prevalence at first (index) colonoscopy. We investigate the prevalence and endoscopist detection rates of SSPs in a large cohort of patients undergoing index diagnostic colonoscopy. Methods: We retrospectively analysed a prospective, quality assurance database of all patients undergoing colonoscopy at a single academic centre between December 2014 and March 2017. We included consecutive, outpatient colonoscopy for diagnostic indications, and no history of previous colonoscopy. We excluded previous colonoscopy or previous colorectal resection, and high risk indications (positive faecal immunochemical test, referral for therapeutic colonoscopy, IBD, hereditary cancer syndromes, known polyposis syndrome, and family history of polyps or CRC. We also excluded patients with inadequate bowel preparation, incomplete procedures. Polyp prevalence was calculated, together with endoscopist detection rates for adenomas and SSPs. We used multiple logistic regression to model predictors of adenoma and sessile serrated polyp detection. Results: A total of 3062 index, diagnostic colonoscopies were performed over 28 months (1488 in patients aged ≥50 and 1574 in patients aged <50. The mean age for adults≥50 was 62.5 ± 9.4 years (57.7% females) and 36.8±8.7 years (60.6% females) in adults <50. The overall unit detection rates of adenomas and sessile serrated polyps in adults <50 was 22% and 13.4%, respectively, compared with 52.4% and 16% in adults≥50. On multiple logistic regression analyses, age, gender and endoscopist were independently predictive of adenoma detection in both adults <50 and ≥50 years (both P<0.001). However, only the endoscopist was associated with SSP detection in adults <50 (P<0.001) compared to both the endoscopist (P<0.001) and age (P=0.023) in adults≥50. Conclusion: In adults aged under 50 years undergoing index diagnostic colonoscopy, the prevalence of sessile serrated polyps and adenomas is substantial. Detection of SSPs was highly variable and endoscopist dependent. These findings emphasise the importance of high-quality colonoscopy, but also raise questions about the target age for CRC screening programs and the biology of the serrated pathway of colorectal carcinogenesis.Table: Table. Overall unit detection rates