Emergency Departments – When It's Not Just About Waiting But Also About Sharing…

Background: Although hospital-acquired infections are an important risk for the health of hospitalized patients, there is no publication evaluating the risk of infection attributable to an emergency department (ED) visit. Elderly long-term care facility (LTCF) residents have multiple chronic diseases that predispose them to infection. They may require more ED visits, have longer stays and are more likely to be cared for in multi-bed observation areas and corridors. They are thus the population in which the risk is most likely to be measurable.. Objective: We aimed to determine the risk of infection associated with an ED visit. Methods: A multicentric retrospective cohort involving elderly residents in LTCF from the provinces of Quebec and Ontario was followed to compare rates of new infections in those with and without ED visits. Participating LTCF identified ED-exposed patients. New infections (respiratory tract [RTI] and gastro-intestinal [GI]) were detected by LTCF chart reviews for compatible symptoms occurring between day 2 and 7 following an ED visit for a non-infectious illness. For each ED-exposed case, 2 matched ED-unexposed residents (unit within the LTCF, age (±5 years), and sex) were randomly selected. The surveillance period for the development of new infections in unexposed patients was the same as exposed patients (total 5 days). This study covered the periods from September to May of two consecutive years (2006-2008). Rates and proportions of new infections were calculated in both groups and conditional logistic regression was used to adjust for potential confounders.

Results: A total of 1213 elderly LTCF residents were enrolled in the study – 393 exposed and 820 unexposed. Baseline characteristics of both groups were similar in terms of number of roommates, sick roommates, smoking status, and influenza and pneumococcal vaccination status but differed in terms of underlying health. The average Charlson Comorbidity index (CCI) was lower in ED unexposed (5.59) than in ED exposed (6.19) p = 0.0003. Patients exposed to EDs also received more visitors in the days following their return compared to those who never left (47.3% vs. 37.6% p = 0.02). When looking at the risk of either a RTI or GI infections between day 2 and 7 following ED return, 10 (1.2%) residents in the unexposed compared to 21 (5.3%) in the exposed group developed a new infection. The incidence of newly acquired infections was 1.7 and 7.6/1,000 patient-days in the unexposed and exposed group respectively. The crude hazard ratio (HR) for the risk of infection following an ED visit was 4.5 (95%CI 2.1– 9.9). Once adjusted for the presence of visitors upon return to the LTCF and the CCI, the HR of ED exposure was 5.3 (95%CI 2.0 – 14.3).

Conclusions: Visit to EDs is associated with a 5.3-fold increased risk of acquisition of either RTI or GI infections. The ED-returning resident may then become the index case for outbreaks in the LTCF.