A modified colorectal screening score for prediction of advanced neoplasia: A prospective study of 5744 subjects

Background and Aim We validated a modified risk algorithm based on the Asia Pacific Colorectal Screening (APCS) score that included body-mass index (BMI) for prediction of advanced neoplasia. Methods Among 5,744 Chinese asymptomatic screening participants undergoing a colonoscopy in Hong Kong from 2008-2012, a random sample of 3,829 participants acted as the derivation cohort. The odds ratios for significant risk factors identified by binary logistic regression analysis were used to build a scoring system ranging from 0-6, divided into ‘average-risk’(AR):0; ‘moderate-risk’(MR):1-2 and ‘high-risk’(HR):3-6. The other 1,915 subjects formed a validation cohort and the performance of the score was assessed. Results The prevalence of advanced neoplasia in the derivation and validation cohorts was 5.4% and 6.0%, respectively (p=0.395). Old age, male gender, family history of colorectal cancer, smoking and BMI were significant predictors in multivariate regression analysis. A BMI cutoff at >23 kg/m2 had better predictive capability and lower Number Needed to Screen than that of >25 kg/m2. Utilizing the score developed, 8.4%, 57.4% and 34.2% in the validation cohort were categorized as AR, MR and HR, respectively. The corresponding prevalence of advanced neoplasia was 3.8%, 4.3% and 9.3%. Subjects in the MR and HR group had 1.24 and 2.48-fold increased prevalence of advanced neoplasia than the AR group. The c-statistics of the modified score had better discriminatory capability than that using predictors of APCS alone (c-statistics=0.65 vs. 0.60). Conclusions Incorporating BMI into the predictors of APCS score was found to improve risk prediction of advanced neoplasia and reduce colonoscopy resources.