Delirium is defined as an acute disturbance in attention, awareness, and cognition that arises as a direct consequence of a physiological event such as an acute illness or infection. It affects roughly one in four older acute medical inpatients, a figure that has remained stubbornly stable across four decades of research. Far from being a benign and transient confusion, delirium is a red flag of underlying vulnerability. It is associated with increased mortality, longer hospital admissions, long-term cognitive decline, poorer functional status, and higher rates of institutionalisation. Crucially, it is also partially preventable: studies suggest that up to a third of new delirium cases in hospitalised patients could be avoided through multicomponent interventions such as reorientation, sleep protection, early mobilisation, and ensuring patients have their glasses and hearing aids. But prevention depends on knowing who is at risk, and that is where the system frequently breaks down.

The Groningen team, led by geriatric medicine researcher Maaike A. Pouw, set out to compare three distinct approaches to delirium identification in the same cohort of patients. The first was a retrospective extraction of documented prehospital indicators: researchers combed through the free-text referral notes and handovers written by general practitioners and ambulance professionals, marking a case as positive when the notes contained an explicit suspicion of delirium or descriptions consistent with it, such as a patient being progressively confused, disoriented, or incoherent. The second was the VMS delirium risk score, a three-question tool used across Dutch hospitals since 2012 that asks about memory problems, need for help with self-care, and any previous episode of delirium. The third was the 4AT, a widely validated four-item screening instrument that assesses alertness, abbreviated mental test performance, attention, and acute mental status change, and can be administered without special training even to drowsy or agitated patients.

The study drew on Acutelines, a hospital-based data and biobank that enrols patients with acute conditions arriving at the emergency department of the University Medical Center Groningen. From September 2020 to February 2024, the researchers included patients aged 70 and older who were admitted for at least one night after their emergency visit and who had a completed 4AT assessment at admission. In total, 655 patients entered the analysis, with a median age of 76 years and 62 percent male. To establish whether patients actually experienced delirium during hospitalisation, the team performed a careful chart-based review using DSM-5 criteria, supplemented by a check for new antipsychotic prescriptions or elevated scores on the Delirium Observation Screening Scale. Uncertain cases were discussed in consensus meetings, a process that applied to 20 percent of all records.

The headline finding was stark. Delirium occurred in 146 of the 655 patients, or 22 percent, consistent with the well-documented burden of the syndrome in older inpatients. When the researchers calculated positive likelihood ratios, a statistical measure of how strongly a positive result points toward the condition, the documented prehospital indicators scored 5.54, the 4AT scored 2.39, and the VMS risk assessment scored just 1.55. In practical terms, when a general practitioner or ambulance medic had written down a suspicion of delirium, that observation was by far the strongest early predictor that the patient would indeed be delirious during the admission. The positive predictive value of the prehospital documentation was 0.64, meaning nearly two-thirds of flagged patients were confirmed cases, and the 4AT achieved an even higher positive predictive value of 0.83, although it flagged only 22 percent of patients as positive.

Each tool, however, told only part of the story. The documented prehospital indicators had a low sensitivity of 0.34, meaning most patients who went on to develop delirium had no such note in their referral documentation. The researchers caution that this may partly reflect documentation gaps rather than a true absence of symptoms at the time of prehospital contact, since emergency crews understandably prioritise physical stabilisation and may not record or convey observations of confusion during a hectic transfer. Among patients with negative prehospital indicators, 16 percent still developed delirium, a figure similar to the 13 percent false-negative rate of the 4AT. The VMS score behaved differently altogether: as a risk-factor-based tool rather than a feature-based one, it generated many false positives, 231 patients or 38 percent of the cohort, but relatively few false negatives, suggesting it is better suited to casting a wide preventive net than to confirming diagnosis.

The study also revealed troubling inconsistencies in routine screening practice. Although compliance with VMS screening was high at 94 percent, exceeding expectations from prior literature, discrepancies appeared in 12 percent of cases. Some patients had been screened twice at different time points with contradictory answers, and in other instances the screening indicated the patient had never experienced delirium even though a previous episode was clearly documented in their medical history. The authors suggest this may reflect the tool’s reliance on patient self-report, since patients may not recall a previous delirium episode, particularly when it occurred on top of underlying dementia. These reliability concerns matter because the VMS score drives decisions about preventive care across Dutch hospitals.

Another striking observation was the limited overlap between the two feature-based approaches. Both the prehospital documentation and the 4AT aim to capture the actual clinical features of delirium at roughly the same point in the care pathway, yet their positive classifications diverged substantially. The authors attribute this to the inherently fluctuating course of delirium, differences in assessment timing, and the possibility that early symptoms resolve quickly after simple interventions such as intravenous fluids or oxygen. They also note that research settings tend to yield higher detection rates than routine care, and that the 4AT in this study was administered partly by trained researchers rather than solely by clinical staff.

The implications reach beyond the emergency department. The authors argue that it would be beneficial to mandate the documentation of cognitive functioning in referral letters and ambulance reports for older patients conveyed to the emergency department, potentially enabling earlier identification and faster intervention, such as involving family members or placing the patient in a calmer environment. They point to emerging technologies that could help, including targeted training for emergency medical services personnel, clinical decision support systems, and natural language processing tools capable of extracting relevant information from clinical narratives automatically. The Institute for Healthcare Improvement recommends delirium screening at least every 12 hours in acute care, but the Groningen team suggests assessment may need to begin even earlier, at the first point of contact at home or in the ambulance.

The study has limitations that the authors acknowledge candidly. It was a single-centre cohort, the medical records were not independently assessed by two reviewers, and the retrospective design meant outcome parameters were restricted to what could be extracted from electronic records. Verbal observations communicated at handover may never have been written down, and chart-based delirium detection depends on the recognition skills of the initial care provider. The interval between early assessment and the occurrence of delirium during a long hospital stay also complicates interpretation, since an initially negative assessment may have been accurate at the time. Nevertheless, the large sample size, multi-year data collection, and realistic representation of routine emergency practice give the findings weight. As the researchers conclude, all three approaches were associated with delirium during hospitalisation, but the humble prehospital note, often scribbled under pressure in the back of an ambulance, may be an underused and valuable asset in protecting older patients from one of medicine’s most consequential syndromes.

Subject of Research: Comparison of three delirium identification approaches in older emergency department patients

Article Title: Comparing three approaches to delirium identification in older patients presenting to the emergency department

Article References: Pouw, M. A., Haan, E. G., Jansen, C. J., Trzpis, M., & van Munster, B. C. (2026). Comparing three approaches to delirium identification in older patients presenting to the emergency department. European Geriatric Medicine. https://doi.org/10.1007/s41999-026-01612-w

Image Credits: AI Generated

DOI: 10.1007/s41999-026-01612-w

Keywords: delirium, emergency department, older patients, 4AT screening, VMS risk score, prehospital care, geriatric medicine, screening tools, likelihood ratio, hospitalisation, cognitive impairment, ambulance notes