Epidemiology and Factors Associated With Discharging Patients After Blood Culture Collection in the Emergency Department: A Case-Control Study in Japan

Background. Some patients receive the diagnosis of bloodstream infection (BSI) after discharge from the emergency room (ER). Because the safety of discharging patients after a blood culture collection is unknown, the present study aimed to investigate the prevalence, outcomes, and factors associated with BSI diagnosed after ER discharge. Methods. This monocentric, case-control study compared patients who received a BSI diagnosis after ER discharge with those who were admitted for BSI. Factors associated with ER discharge after a blood culture collection were identified using multivariate logistic regression analysis. Results. Between January 2014 and December 2020, 5.5% (142/2575) of patients with BSI visiting the ER were initially discharged. This occurred more commonly during the coronavirus disease 2019 (COVID-19) pandemic in 2020. On multivariate analysis, factors independently associated with the discharge of patients with BSI were the absence of hypotension (adjusted odds ratio [aOR], 15.71 [95% confidence interval {CI}, 3.45-71.63]), absence of altered mental status in the ER (aOR, 8.99 [95% CI, 3.49-23.14]), unknown origin at ER discharge (aOR, 4.60 [95% CI, 2.43-8.72]), and low C-reactive protein (aOR, 3.60 [95% CI, 2.19-5.93]). No difference in 28-day mortality was observed between the groups. Conclusions. BSI is occasionally diagnosed after ER discharge. The prevalence of BSI diagnosed after ER discharge may have increased during the COVID-19 pandemic. Normal vital signs, unknown origin at ER discharge, and low C-reactive protein were important considerations leading to the discharge of these patients.