Esophagogastroduodenoscopy is crucial for early detection of upper gastrointestinal neoplasms (UGN) and preneoplastic lesions. With growing demand, training new endoscopists is essential. We aimed to evaluate the impact of trainee involvement in gastroscopy on key quality indicators and the detection of upper gastrointestinal abnormalities, and to assess how endoscopic training settings may influence diagnostic performance.

We retrospectively analyzed 6,540 gastroscopies performed between January 2019 and December 2021 at two academic centers (663 with trainee participation).  Quality indicators included Endoscopist Biopsy Rate (EBR), Composite Detection Rate (CDR), and UGN. Group comparisons used Mann–Whitney, χ², or Fisher’s exact tests. Logistic regression identified factors associated with upper GI pathology and EBR, UGN, and CDR; variables with p < 0.1 entered multivariate models. Analyses used IBM SPSS Statistics.

Overall, 57.89% of procedures were outpatient, the median patient age was 61 years (IQR 23), and 54.86% of patients were female. A high-definition (HD) endoscope was used in 62.92% of all procedures. The presence of a trainee did not significantly affect UGN (OR = 1.24; 95% CI: 0.90-1.72; p = 0.192), EBR (OR = 1.05; 95% CI: 0.88-1.25; p = 0.614), or CDR (OR = 1.01; 95% CI: 0.85-1.21; p = 0.872). Similarly, no significant differences were observed in the detection rates of cancers (p = 0.53), dysplasia (p = 0.198), and gastric precancerous conditions (p = 0.234) between procedures with and without trainee involvement. In the multivariate analysis, the factors associated with higher odds of UGN included age (OR = 1.02; 95% CI: 1.01-1.02; p < 0.001), use of an HD endoscope (OR = 1.62; 95% CI: 1.09-2.55; p = 0.017), sedation (OR = 1.22; 95% CI: 0.80-1.87; p < 0.001), alarm symptoms (OR = 3.66; 95% CI: 2.90-4.62; p < 0.001), and outpatient setting (OR = 1.57; 95% CI: 1.41-1.75; p < 0.001), while female sex was associated with a lower risk of UGN (OR = 0.70; 95% CI: 0.57-0.87; p = 0.001). Regarding EBR, multivariate regression analysis demonstrated that age (OR = 1.00; 95% CI: 1.00-1.01; p < 0.001), female sex (OR = 1.20; 95% CI: 1.08-1.34; p < 0.001), use of an HD endoscope (OR = 2.86; 95% CI: 2.28-3.58; p < 0.001), and outpatient setting (OR = 1.44; 95% CI: 1.28-1.61; p < 0.001) were associated with higher odds of EBR, while sedation was associated with lower (OR = 0.78; 95% CI: 0.63-0.98; p = 0.033). For CDR, multivariate regression analysis indicated that age (OR = 1.02; 95% CI: 1.01-1.02; p < 0.001), female sex (OR = 1.29; 95% CI: 1.16-1.44; p < 0.001), use of an HD endoscope (OR = 1.57; 95% CI: 1.23-2.00; p < 0.001), sedation (OR = 1.69; 95% CI: 1.32-2.16; p < 0.001), and outpatient setting (OR = 1.44; 95% CI: 1.28-1.61; p < 0.001) were significantly associated with higher CDR, whereas the presence of alarm symptoms was significantly associated with lower CDR (OR = 0.74; 95% CI: 0.63-0.87; p < 0.001).

These results indicate that trainee involvement does not compromise the quality of gastroscopy, supporting the safe integration of training into routine practice.