OSATS scoring confirms ICG enhancement of performance in laparoscopic radical gastrectomy: a post-hoc analysis of a randomized controlled trial

Background: Indocyanine green (ICG) fluorescence imaging is effective in increasing the number of lymph node dissections during laparoscopic radical gastrectomy; however, no studies have attempted to explain this phenomenon. Methods: This study utilized the data from a previous randomized controlled trial (FUGES-012 study) investigating ICG-guided laparoscopic radical gastrectomy performed between November 2018 and July 2019. The Objective Structured Assessments of Technical Skills (OSATS) scoring system was used to grade videos from the ICG and non-ICG groups. Patients with an OSATS score >29 were classified as the high-OSATS population, while those with an OSATS score ≤29 were classified as the low-OSATS population. Results: A total of 258 patients were included in the modified intention-to-treat analysis: 129 in the ICG group and 129 in the non-ICG group. The OSATS score of the ICG group was higher than that of the non-ICG group (29.6 ± 2.6 vs. 26.6 ± 3.6; P <0.001). The ICG group underwent a significantly higher mean total number of lymph node dissections than the non-ICG group (50.5 ± 15.9 vs. 42.0 ± 10.3; adjusted P <0.001). The group assigned to ICG use, better OSATS (high-OSATS) scores were observed, which correlated with greater D2 lymph node retrieval (54.1±15.0 vs. 47.2±8.7; adjusted P =0.039). Finally, the ICG group had a lower rate of lymph node non-compliance than that of the non-ICG group (31.8% vs. 57.4%; P <0.001). Conclusions: By applying ICG fluorescence navigation technique, better OSATS scores were observed, which correlated with greater lymph node retrieval and lower lymph node non-compliance rate, as recommended for individualized laparoscopic radical gastrectomy.