Age-Specific Colonoscopic Yield and Symptom-Based Risk Stratification in Symptomatic Adults: A Bicenter Omani Analysis to Inform Early Detection and Screening Strategies for Colorectal Neoplasia

<i>Background and Objectives</i>: Colorectal cancer (CRC) is the most common gastrointestinal malignancy in Oman and among the top three cancers nationally, with an increasing burden of early-onset CRC (EOCRC) diagnosed before age 50. Despite national CRC guidelines, the lack of an organized screening program means most cases are detected symptomatically and at advanced stages. This study evaluated age-related differences in colonoscopic findings and advanced neoplasia risk in symptomatic adults to inform early detection and screening strategy development. <i>Materials and Methods</i>: A cross-sectional analysis of 2041 colonoscopies performed at two national tertiary referral centers, Sultan Qaboos University Hospital and Royal Hospital, was conducted (2018-2021). Patients were categorized by age (<50 vs. ≥50 years). Outcomes included adenoma detection rate (ADR), advanced premalignant lesions (APL), colorectal cancer (CRC), and advanced colorectal neoplasia (ACRN; APL and/or CRC). Associations between presenting symptoms and ACRN were analyzed using univariable logistic regression, and diagnostic yield was estimated via number needed to scope (NNS). The cohort was predominantly symptomatic (71.9%), with 15.8% screening and 12.3% surveillance procedures. <i>Results</i>: Of 2041 procedures, 742 (36.3%) were in patients <50 years. ADR, APL, CRC, and ACRN were significantly higher in those ≥50 years (14.9%, 7.5%, 5.8%, and 13.3%) than in younger adults (8.5%, 3.2%, 2.7%, and 5.9%; all <i>p</i> < 0.01). Among younger adults, rectal bleeding (OR 2.17, 95% CI 1.15-4.08, <i>p</i> = 0.026) and abdominal pain (OR 2.14, 95% CI 1.15-3.98, <i>p</i> = 0.022) were significantly associated with ACRN. Diagnostic efficiency (NNS) was highest for loss of appetite in both age groups (4.7 in <50 vs. 2.8 in ≥50 years). Despite lower overall rates, a substantial burden of advanced neoplasia was observed in symptomatic adults <50 years (5.9% ACRN, 2.7% CRC). <i>Conclusions</i>: This bicenter study demonstrates clear age-related disparities in colorectal neoplasia, with a clinically important burden of advanced disease in symptomatic adults under 50 years. These findings highlight the importance of prompt colonoscopic evaluation for younger adults presenting with alarm symptoms, particularly rectal bleeding and abdominal pain, and provide evidence supporting risk-stratified diagnostic approaches. While age-related differences suggest potential value in earlier screening initiation, our predominantly symptomatic tertiary care cohort cannot directly determine optimal screening age thresholds. Prospective screening trials and cost-effectiveness analyses are needed to establish population-based detection rates and inform evidence-based screening policy development in Oman.