Intensive care units are designed to be places of vigilance, monitoring, and rescue, yet they are also among the most dangerous workplaces in modern medicine. A new study from University Hospital Basel in Switzerland has now quantified just how tightly violence in the ICU is entangled with one of the most common and feared complications of critical illness: delirium. In an analysis of more than ten thousand patient admissions, researchers found that when nurses documented aggressive or violent behavior toward healthcare workers, nearly nine out of ten of those patients had experienced delirium within a seventy-two-hour window surrounding the incident, and more than three-quarters were actively delirious at the very moment the event occurred. The findings, drawn from the CAVE study, suggest that the brain failure of critical illness may be the single most important warning sign preceding assaults on ICU staff.
The research team, led by Sebastian Berger and Raoul Sutter, conducted a retrospective observational cohort study covering the years 2023 and 2024 at the University Hospital Basel, one of Switzerland’s largest tertiary care centers. The investigators combed through nursing documentation for every incident in which a patient was reported as aggressive or violent toward staff, then linked those events to a rich set of clinical variables: demographics, treatment characteristics, sedation and restraint use, and standardized neurological scores. Two scoring systems anchored the analysis. The Richmond Agitation-Sedation Score, or RASS, grades a patient’s level of agitation from deep sedation to extreme combativeness, while the Intensive Care Delirium Screening Checklist, known as the ICDSC, detects the fluctuating inattention and disorganized thinking that define delirium.
The headline numbers are striking in their clarity. Of 10,817 ICU patients treated during the study period, 300, or 2.8 percent, were documented as aggressive or violent toward healthcare workers. That figure may sound modest, but its concentration is what matters: delirium occurred in 89.3 percent of those patients within seventy-two hours of the event, and 76.7 percent were delirious at the time of the incident itself. In other words, violence in this ICU was almost never a random act by a fully lucid patient. It was overwhelmingly a symptom of an injured, inflamed, or medicated brain losing its grip on reality, perception, and impulse control.
The study also mapped the anatomy of these incidents in unusual detail. The vast majority of events, 80.4 percent, were physical rather than purely verbal, ranging from grabbing and hitting to more dangerous assaults. Crucially, in 22.2 percent of cases, the violent episode was preceded by a documented phase of lesser aggression, with a median interval of 21.6 hours between the first signs of hostility and the full-blown violent event. This prodromal window is arguably the most clinically actionable finding in the entire study. It means that in roughly one in five cases, staff had a day or more of warning, recorded in the chart, before a patient crossed the line from agitation into violence.
When the researchers turned to statistical modeling, they used both univariable and multivariable logistic regression to separate genuine independent associations from mere correlations. Two variables survived the adjustment: rising RASS and rising ICDSC scores in the period before the violent incident. Each one-point increase in RASS carried an odds ratio of 1.46 for subsequent violence, a highly significant association with a p-value of 0.001. Each one-point increase in the ICDSC carried an odds ratio of 1.14, with a p-value of 0.039. Translated into bedside practice, this means that a patient whose agitation score is climbing, and whose delirium screen is deteriorating, is measurably more likely to assault a nurse or physician within hours, even after accounting for age, illness severity, comorbidities, and treatment factors.
The trajectory of how staff responded to these events reveals an uncomfortable pattern in current ICU practice. When patients were merely aggressive, the response leaned heavily on verbal de-escalation, the least invasive and most patient-centered tool available. But once behavior escalated to outright violence, management shifted dramatically toward restrictive measures. Sedation rates jumped from 45.3 percent during the aggressive phase to 69.8 percent after violence occurred, a difference that was highly statistically significant. Physical restraint use more than doubled, rising from 20.0 percent to 43.1 percent. These are not trivial interventions: heavy sedation in a delirious patient can prolong brain dysfunction, delay weaning from mechanical ventilation, and extend length of stay, while physical restraint is itself a known trigger for worsening agitation, psychological distress, and even physical injury.
Perhaps most sobering is the complication rate attached to that response. Sedation-related complications were documented in 64.9 percent of the violent episodes, meaning nearly two-thirds of these crises were managed in a way that carried its own medical cost. The study also noted that one-on-one nursing rates did not change around these events, which the authors interpret as evidence that the system relies on restrictive measures, drugs, and straps, rather than on increasing staffing or dedicated observation when a patient begins to spiral. In an era when ICU delirium guidelines emphasize non-pharmacological prevention, early mobilization, reorientation, sleep protection, and family presence, the Basel data suggest that the reality of a violent crisis still pulls teams toward the pharmacological hammer.
The implications reach well beyond a single Swiss hospital. Workplace violence against healthcare workers has become a growing concern for organizations such as the World Health Organization and the International Council of Nurses, and the ICU is a recognized hotspot because patients there are frequently intubated, sedated, withdrawn from alcohol or drugs, or suffering from metabolic and infectious derangements that attack cognition. What the CAVE study adds is a quantified, score-based early warning system hiding in plain sight. Nurses already calculate RASS multiple times per shift and screen for delirium with the ICDSC as part of routine care. The new findings suggest that these same numbers, tracked over time, could function as a predictive dashboard: a rising trajectory, rather than any single value, flags a patient at escalating risk of harming staff.
Such a predictive approach would fit naturally into existing ICU safety workflows. A patient whose RASS climbs from calm to restless, and whose ICDSC ticks upward across consecutive screens, could automatically trigger a bundle of proactive measures: early involvement of a delirium specialist, review of reversible causes such as hypoxia, infection, pain, or withdrawal, minimization of deliriogenic medications like benzodiazepines, increased family presence and reorientation, and a planned de-escalation strategy before the situation becomes physical. The 21.6-hour median prodromal interval documented in the study suggests there is often real time to act, provided the warning signs are recognized as such rather than charted as isolated irritability. The authors argue that identifying these early signs could allow proactive, de-escalating intervention and potentially reduce the need for physical restraints and heavy sedation, breaking the cycle in which restraint breeds agitation and agitation breeds restraint.
Limitations temper the enthusiasm, as they do in any retrospective single-center study. The analysis relied on nursing documentation, which may undercount incidents, since workplace violence in hospitals is notoriously underreported, and the 2.8 percent incidence likely represents a floor rather than a ceiling. The data come from one large academic ICU, and staffing patterns, sedation protocols, and reporting cultures elsewhere may differ. The study period covered 2023 and 2024, and the published version notes that the article was shared early as an accepted manuscript subject to final edits. Still, the core signal is robust and biologically plausible: delirium, the acute brain failure that affects a large fraction of mechanically ventilated and critically ill patients, is the dominant context in which ICU patients lash out at the people caring for them. If the rising RASS and ICDSC scores that precede violence can be turned into an automated alert, the CAVE study may mark a shift from reacting to ICU violence with sedatives and straps toward preventing it with vigilance, early recognition, and humane de-escalation, protecting both the patients whose brains are failing and the nurses and physicians standing at their bedsides.
Subject of Research: Delirium-associated aggression and violence toward healthcare workers in the intensive care unit
Article Title: Incidence and predictors of delirium-associated violence towards healthcare workers in a Swiss ICU: results from the CAVE study
Article References: Berger, S., Frei, A. I., Grzonka, P., Amacher, S. A., Gebhard, C. E., Hunziker, S., & Sutter, R. (2026). Incidence and predictors of delirium-associated violence towards healthcare workers in a Swiss ICU: results from the CAVE study. BMC Medicine. https://doi.org/10.1186/s12916-026-05291-z
Image Credits: AI Generated
DOI: 10.1186/s12916-026-05291-z
Keywords: delirium, ICU, workplace violence, RASS, ICDSC, aggression, sedation, physical restraint, de-escalation, critical care, patient safety, nursing
