Impact of Anticipated Blood Sampling on Length of Stay in Emergency Department: a Single-center Observational Retrospective Study With Propensity Score Matching.

The number of emergency department visits is constantly increasing France. Over the past three decades, the figure has risen from 10 million to more than 20 million visits per year. This is often attributed to a shortage of available primary care physicians and patients' inability to obtain timely appointments, whether for general practice or specialist consultations. It should also be noted that following the COVID-19 pandemic, the resurgence in emergency department attendance has further strained services. An aging population is associated with more advanced chronic conditions that are prone to decompensation, as well as more frequent acute illnesses resulting from increasing age-related frailty.

In France, the healthcare system encompasses 719 emergency departments, predominantly located in public healthcare institutions. Emergency departments manage medical, psychiatric, surgical, and traumatological emergencies in both children and adults. The current context is further characterized by a reduction in the number of available downstream inpatient beds nationwide, with an average decrease of approximately 1,390 beds per year between 2014 and 2023.

These various factors contribute to high emergency department utilization rates and occupancy levels. Emergency department length of stay has been shown to impact in-hospital mortality, particularly among patients aged 75 and over, and also negatively affects patient experience as well as the mental health of healthcare workers. One of the key challenges is to identify ways of reducing emergency department length of stay in order to improve patient flow and thereby decrease occupancy rates. Better control of these factors may also reduce morbidity and mortality associated with overcrowded emergency departments, as well as mean inpatient length of stay.

Emergency department length of stay depends on multiple factors, including waiting time before triage and placement, time to medical advice, time to blood sampling and imaging results when ordered, and time to specialist consultation when required. Additional delays may also arise from waiting for an inpatient bed to become available. All of these steps affect length of stay but are necessary to establish an accurate diagnosis and determine the appropriate disposition for each patient. Triage, using the FRENCH scale applied to patients in this study, may itself have an impact when performed rigorously, although blood tests have been shown to outperform algorithm-based triage in predicting short-term mortality. However, when unnecessary tests are performed through systematic blood sampling, emergency department length of stay is prolonged.

In the study by Strada, which evaluated anticipated blood sampling for abdominal pain, chest pain, and non-traumatic bleeding, a benefit was identified only for chest pain. Another study, conducted on a small sample, found no influence of blood testing on emergency department length of stay.

A further study evaluated point-of-care testing in the emergency department, which significantly reduced the time between test ordering and result availability, but demonstrated no impact on emergency department length of stay.

At the emergency department of the Centre Hospitalier de Roubaix, an increase in admissions and time to first medical contact has been observed, and several protocols have already been implemented to improve length of stay. Since November 2024, a high-flow procedure has been introduced enabling anticipated blood sampling prior to the first medical contact.

The primary objective of the study is to evaluate the impact of anticipated blood sampling on emergency department length of stay. Secondary objectives include the impact of anticipated blood sampling on length of stay according to patient disposition, and its impact on time to first medical contact.