Pil Joo: Effect of in-patient antibiotic treatment among delirious older adults found with a positive urine test: a cohort study


It is common practice to investigate for urinary tract infections (UTI) in older adult patients presenting with delirium even in the absence of reported urinary symptoms. It remains unclear whether an UTI can cause delirium without associated urinary symptoms such as dysuria or urinary frequency. 

Joo et al. performed a systematic review to determine if treatment of delirious, older hospital in-patients with bacteriuria and no symptoms specific to the urinary system improved delirium itself. It identified a single observational trial with an inconclusive outcome. There were no randomized controlled trials that met the inclusion criteria. Ultimately, there is a deficiency in clinical evidence to inform future studies and recommendations on delirium and asymptomatic bacteriuria.


This observational study aims to assess whether antibiotic treatment of patients admitted to hospital from the Emergency Department (ED) for delirium with a positive urine test is correlated with the proportion of delirium resolution by day 7 after admission. We hypothesize that antibiotic treatment will not increase the rate of delirium resolution. Furthermore, we hypothesize that antibiotic treatment may be correlated to slower resolution and increased prevalence of C. difficile infection, compared to the non-treated cohort. 


Patient selection

Patients sixty-five years of age and older presenting to the ED of The Ottawa Hospital’s Civic and General Campus with a primary complaint of delirium and are admitted to family medicine or internal medicine in-patient services will be screened for possible inclusion. ED chart, especially the chief complaint, “History of Present Illness” section and the nursing note will be reviewed to ensure that the primary complaint is consistent with delirium or approximate synonym. We will collect 3D-CAM score performed by nurses in the admitting services. The 3D-CAM instrument is a validated diagnostic tool for delirium which can be completed in a median of 3 minutes and has sensitivity of 95% and specificity of 94%. 


The primary outcome measured in this study will be the difference in rate of delirium measured by 3D-CAM on day 7 of admission in those who received antibiotics compared to those who did not. Secondary outcomes will include daily delirium rate up to day 6, C. difficile infection rate, other antibiotic related side effects, length of hospital stay, mortality, and “Awaiting for Long-term Care” (ALC) designation (among those who are from independent living environment prior to admission). 

Data Collection

TOH electronic medical record (EPIC) and CareConnectOntario system will be used to collect the 3D-CAM scores, other outcomes of interest, and baseline data.

Analysis and Interpretation

The primary outcome (difference in rate of delirium resolution by 3D-CAM) will be analyzed with Fisher’s exact test or χ2 test. 

Impact on EM

This observational study and subsequent RCT will offer valuable evidence into this common presentation to ED. We hope to answer whether obtaining urine sample or treating with antibiotics for suspected UTI will improve the symptoms of delirium.