Endoscopic Surveillance on a High-risk Population for Gastric Cancer in Latin America: The ECHOS Cohort Study.

The Endoscopic Cohort and Histological OLGA staging (ECHOS) study is a retrospective longitudinal cohort developed in the Pontificia Universidad Católica de Chile health care system, an open health care system with 3 endoscopic units in Santiago, Chile. Patients 18 years or older were eligible for the study if they had at least one non-urgent outpatient EGD with gastric biopsies collected following the USSBP between June 2015 and June 2021. The baseline EGD was defined as the earliest examination conducted between this time frame that met inclusion criteria. Participants were included in the cohort if they underwent a subsequent "surveillance" EGD. In order for the subsequent EGD to qualify as surveillance, it needed to occur at least 6 months after the baseline EGD and include gastric biopsies collected according to the USSBP; one exception to the USSBP requirement was if HGD or GA was detected on the surveillance (i.e. non-baseline) EGD. Patients with prior history of HGD or any type of gastric malignancy, gastrectomy or non-gastric active malignancy were excluded. Also, patients with HGD or GA on the baseline EGD were excluded. Patients with indefinite (IND) or low-grade dysplasia (LGD) on the baseline EGD were considered for the cohort.