Prediction Model for Risk of Adenoma at Screening Colonoscopy

Aim: To identify risk factors for adenomatous polyps and develop an adenoma prediction model in individuals undergoing screening colonoscopy. Methods: We extracted demographic data, smoking history, current aspirin use and family history of colorectal cancer (CRC) as well as colonoscopy and histopathology results from individuals who underwent screening colonoscopy at the Minneapolis VA Medical Center between 2007 and 2012. Results: 3000 veterans were included. Adenomas were found in 1,063 patients (35%). Advanced adenomas were seen in 248 patients (8%). Risk factors for adenoma: age (OR 1.02, 95% CI 1.01, 1.03), male sex (OR 2.26, 95% CI 1.50, 3.52), and smoking (OR 1.53, 95% CI 1.29, 1.83). Risk factors for advanced adenoma: male sex (OR 3.79, 95% CI 1.18, 23.2) and smoking (OR 1.61, 95% CI 1.10, 2.34). Variables included in the final model were age, sex, BMI, race, use of aspirin, smoking history, and family history of CRC. The adjusted AUROCC for adenoma was 0.532 (95% CI 0.517, 0.554) and for advanced adenoma 0.613 (95% CI 0.564, 0.651). Conclusion: The model can be used to predict the risk of adenoma at screening colonoscopy and identify those patients who will benefit most from screening colonoscopy.