Abstract 237: Effect of Hospital Arrival Time on Mortality Rate in Pediatric Patients With Severe Trauma: A Nationwide Database Study in Japan

Introduction: Previous studies have reported that hospital arrival during nighttime was associated with worse outcomes in critically ill pediatric patients. However, this “nighttime effect” in pediatric patients with severe trauma has not yet been well-investigated. Hypothesis: We hypothesized that hospital arrival during nighttime is associated with higher mortality rates in pediatric patients with severe trauma. Methods: We conducted a nationwide retrospective cohort study in Japan from 2004 to 2019 using the Japan Trauma Data Bank, a nationwide trauma registry. Patients who were aged <18 years and had an Injury Severity Score (ISS) >15 were included. Patients with cardiac arrest on hospital arrival were excluded. Hospital arrival was categorized into daytime (from 8:00 am to 4:59 pm) arrival and nighttime (from 5:00 pm to 7:59 am) arrival. The main outcome was the in-hospital mortality rate, and the secondary outcome was the emergency department (ED) mortality rate. As a main analysis, an inverse probability of treatment weighting (IPTW) analysis was performed using propensity scores to adjust for confounders such as age, sex, type of injury, transport time, vital signs, and ISS. In addition, we conducted 1) a subgroup analysis in patients who underwent operation (OP) or interventional radiology (IR) during hospitalization and 2) sensitivity analysis using a multilevel mixed-effects logistic regression model. Results: In total, 6,574 pediatric patients with severe trauma were included, and the overall in-hospital mortality rate was 6.5%. The IPTW analysis showed that compared with daytime arrivals, nighttime arrivals were associated with significantly higher in-hospital mortality (odds ratio [OR], 1.41; 95% confidence interval [CI], 1.09-1.83; P = 0.010) and ED mortality rates (OR, 2.42; 95% CI, 1.07-5.45; P = 0.034) in the entire cohort but not in the subgroup who underwent OP or IR during hospitalization. The sensitivity analysis consistently supported the results of the main analysis. Conclusions: Hospital arrival during nighttime was associated with a higher in-hospital mortality rate in pediatric patients with severe trauma. Further investigations are needed to elucidate the reasons for this “nighttime effect.”