Volume-outcome relationship in pediatric blunt liver and spleen injuries: A multicenter retrospective cohort study

Background The relationship between the number of patients treated in a hospital and patient outcomes (“volume-outcome relationship”) has been reported. We aimed to examine the relationship between hospital case volume and complications, in-hospital mortality, and non-operative management (NOM) failure in pediatric blunt liver and/or spleen injuries (BLSIs). Methods This was a post-hoc analysis of a multicenter retrospective study that enrolled patients aged ≤16 years admitted for BLSIs with Abbreviated Injury Scale grade of at least ≥1 between January 2008 and December 2019. Participating hospitals were categorized into three groups of 33 % each, according to the annual pediatric trauma case volume. We used the Cochrane-Armitage test to determine a linear trend between the hospital case volume and each outcome. Results We identified 1406 patients with BLSIs who were treated at 83 hospitals; 44 (3.1 %) and 12 (0.9 %) patients experienced complications and NOM failure, respectively, with 21 cases (1.5 %) of in-hospital mortality. Hospitals were categorized into high- (28 hospitals), medium- (26 hospitals), and low-volume (29 hospitals) groups. No significant linear trend was observed between hospital volumes and complications (P trend=0.07), in-hospital mortality (P trend=0.67), or NOM failure (P trend=0.57). Sensitivity analyses using different group categorizations provided similar findings. Conclusions This study failed to confirm a volume-outcome relationship between annual pediatric trauma case volume and complications, in-hospital mortality, or NOM failure in pediatric BLSIs in Japan. The limited exposure of Japanese hospitals to pediatric trauma, lack of a system to certify pediatric trauma centers, and practice variations across hospital types potentially underlie these findings.