Validation of a pre-endoscopy risk score for predicting the presence of gastric intestinal metaplasia in a U.S. population

Background and Aims Surveillance of gastric intestinal metaplasia (GIM) may lead to early gastric cancer detection. Our purpose was to externally validate a predictive model for endoscopic GIM previously developed in a veteran population in a second U.S. population. Methods We previously developed a pre-endoscopy risk model for detection of GIM using 423 GIM cases and 1796 controls from the Houston VA Hospital. The model included sex, age, race/ethnicity, smoking, and H. pylori infection with an area under the receiver operating characteristic (AUROC) curve of 0.73 for GIM and 0.82 for extensive GIM. We validated this model in a second cohort of patients from six CHI-St. Luke's hospitals (Houston, Texas) from January-December 2017. Cases were defined as having GIM on any gastric biopsy, and extensive GIM as involving both antrum and corpus. We further optimized the model by pooling both cohorts and assessing discrimination using AUROC. Results The risk model was validated in 215 GIM cases (55 with extensive GIM) and 2469 controls. Cases were older than controls (59.8 vs. 54.7 years) with more non-whites (59.1% vs. 42.0%,) and H. pylori infection (23.7% vs. 10.9%). The model applied to the CHI-St. Luke's cohort had AUROC 0.62 (95% confidence interval [CI] 0.57-0.66) for predicting GIM and AUROC 0.71 (95%CI 0.63-0.79) for extensive GIM. When the VA and CHI-St. Luke's cohorts were pooled, discrimination of both models improved (GIM AUROC 0.74; extensive GIM AUROC 0.82). Conclusion A pre-endoscopy risk prediction model was validated and updated using a second U.S. cohort with robust discrimination for endoscopic GIM. This model should be evaluated in other U.S. populations to risk stratify patients for endoscopic GIM screening.