[Development of a nomogram for predicting the risk of colorectal advanced adenomas]

Objective: To explore the risk factors of colorectal advanced adenomas (AA) and construct a nomogram to predict the risk of colorectal AAs. Methods: Clinical data of patients were retrospectively collected who underwent their first colonoscopy from January 2017 to December 2020 in the First Affiliated Hospital of Nanjing Medical University and were pathologically confirmed harboring colorectal polyps. A credible random split-sample method was used to divide data into training and validation cohorts (split ratio=7∶3). Univariate and multivariate logistic regression analysis were used to identify the predictors of colorectal advanced adenomas, and a nomogram was developed based on the above results. The validation cohort was used for internal validation of the nomogram. The discriminatory value of the nomogram was evaluated using the area under the receiver operating characteristic (ROC) curve (AUC). The consistency between actual outcomes and predicted probabilities was evaluated by the calibration curve. The clinical validity of the model was evaluated by the decision analysis curve (DCA). Results: A total of 1 936 patients with colorectal polyps were eligible. Including 1 356 patients in the training cohort (840 males and 516 females), and 580 patients in the validation cohort (379 males and 201 females), with the mean ages of (57.4±9.8) and (57.6±9.7) years, respectively. There were 1 502 (77.6%) patients without AAs and 434 [22.4%,1-9 mm 73(16.8%) cases、>9-<20 mm 271(62.5%) cases、≥20 mm 90(20.7%) cases] patients with AAs. The regression analysis found that age (OR=1.018, 95%CI:1.003-1.033), fatty liver (OR=1.870, 95%CI:1.274-2.744), low-density lipoprotein (LDL) (OR=1.378, 95%CI:1.159-1.637), fecal occult blood test (FOBT) (OR=2.597, 95%CI:1.857-3.631), and location of adenomas [proximal (OR=2.869, 95%CI:1.727-4.764), distal (OR=2.791, 95%CI:1.721-4.527)] were identified as predictors of colorectal AAs. The AUC of the nomogram was 0.664 (95%CI:0.630-0.698) in the training cohort and 0.640 (95%CI:0.587-0.693) in the validation cohort. The calibration curve showed good consistency between the predicted and actual risk, and the Hosmer-Lemeshow (H-L) test P value was 0.830 and 0.150 in the training cohort and the validation cohort. DCA demonstrated that the nomogram had a better clinical application value. Conclusions: A nomogram with five predictors, including age, fatty liver, LDL, FOBT, and location of adenomas, helped predict the risk of colorectal AAs in patients with polyps and implemented colorectcal cancer stratified screening strategy for colonoscopy in the high-risk population.