- This study investigated whether the ABCDEF bundle improved delirium, functional status, and quality of life in critically ill adults.
- A single-center, pragmatic, randomized controlled trial compared the ABCDEF bundle to usual care in adult ICU patients.
- The bundle did not significantly reduce delirium incidence (37.9% vs. 36.4%, p=0.86) or duration (2.0 vs. 2.5 days, p=0.53).
- The authors concluded the ABCDEF bundle did not reduce delirium incidence or duration in adult ICU patients.
- However, higher scores in 90-day “usual activities” quality of life suggest potential long-term benefits warranting further investigation.
Rethinking ICU Care: The ABCDEF Bundle and Patient Outcomes
Delirium remains a frequent and serious complication in critically ill patients, linked to prolonged intensive care unit (ICU) stays, extended mechanical ventilation, and increased mortality [1]. In response, the ABCDEF bundle (Assess, prevent, and manage pain; Both spontaneous awakening and spontaneous breathing trials; Choice of analgesia and sedation; Delirium: assess, prevent, and manage; Early mobility and exercise; Family engagement and empowerment) has been widely adopted to improve outcomes [2, 3]. While some systematic reviews suggest these bundled interventions can reduce delirium and shorten ICU stays, the evidence is not uniformly consistent [1, 4]. Other studies have highlighted significant challenges in implementation and variable effects on delirium incidence, creating a need for more definitive data [5, 6]. A recent randomized controlled trial provides new clarity on the bundle's specific effects on delirium, functional status, and long-term quality of life in a real-world ICU setting [7].
Study Design and Patient Cohort
The investigation was structured as a single-center, pragmatic, randomized controlled trial, a design intended to evaluate an intervention's effectiveness under everyday clinical conditions rather than idealized research settings. Conducted in an eight-bed medical/surgical ICU in a metropolitan Australian hospital, the study enrolled adult patients expected to require intensive care for at least 48 hours. Participants were randomized to receive either the multicomponent ABCDEF bundle or usual care. A critical finding for clinicians considering implementation was the adherence rate: complete ABCDEF bundle adherence was achieved in only 50% of patients each study day. This figure underscores the practical difficulty of consistently applying all elements of a complex care bundle in a dynamic ICU environment and provides essential context for interpreting the study's primary outcomes.
Primary Outcomes: Delirium Incidence and Duration
The study's primary objective was to assess whether the ABCDEF bundle could reduce the incidence and duration of delirium. Using the Confusion Assessment Method for ICU, the researchers found the intervention had no statistically significant effect on this primary endpoint. The cumulative incidence of delirium was 37.9% in the ABCDEF group compared to 36.4% in the usual care group (odds ratio, 1.1; 95% CI, 0.5–2.2; p = 0.86). Similarly, the bundle did not shorten the duration of delirium episodes. The median duration was 2.0 days (interquartile range [IQR], 1.3–3.5) for the bundle group versus 2.5 days (IQR, 1.0–4.4) for usual care, a nonsignificant difference (mean difference, –0.4 days; 95% CI, –1.6 to 0.8; p = 0.53). These findings indicate that in this trial, the bundle did not alter the course of ICU delirium.
Functional Status at ICU Discharge
The trial also evaluated the bundle's impact on physical function at the time of ICU discharge. This was assessed using the Functional Independence Measure, a standard tool that quantifies a patient's need for assistance with activities of daily living. The results showed no benefit from the intervention on this outcome. The median functional scores were nearly identical between the two arms: 55.0 (IQR, 37.0–67.3) in the ABCDEF group and 53.0 (IQR, 43.8–62.5) in the usual care group. The statistical analysis confirmed no difference between the groups (mean difference, 0.0; 95% CI, –7.7 to 7.6; p = 0.83), indicating that the bundle did not improve functional status at the point of transition from the ICU.
Long-Term Quality of Life Benefits
Despite the lack of effect on in-ICU outcomes, the study revealed a specific long-term benefit when assessing quality of life 90 days after ICU discharge. Using the EuroQol 5D five-level questionnaire, the researchers found that patients in the ABCDEF bundle group reported significantly higher scores in the “usual activities” domain (p < 0.001). This domain evaluates a person's ability to perform routine tasks such as work, study, housework, or leisure activities. This finding suggests the bundle may facilitate a better return to normalcy for survivors of critical illness. It is important to note, however, that this improvement was specific, as no statistically significant differences were observed in the other quality of life domains measured. The authors conclude that while the bundle did not impact the primary outcomes, this potential long-term benefit on patient-centered functional recovery warrants further investigation.
References
1. Dallakoti N, Zhang S, Liu L, Luo Y, Wu Y. Efficacy of Bundle Interventions for the Prevention of Delirium in the Intensive Care Unit: An Umbrella Meta-Analysis of Randomised Clinical Trials and Cohort Studies.. Nursing in critical care. 2025. doi:10.1111/nicc.70192
2. Devlin JW, Skrobik Y, Gélinas C, et al. Clinical Practice Guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption in Adult Patients in the ICU. Critical Care Medicine. 2018. doi:10.1097/ccm.0000000000003299
3. Moraes FDS, Marengo LL, Silva MT, et al. ABCDE and ABCDEF care bundles: A systematic review protocol of the implementation process in intensive care units. Medicine. 2019. doi:10.1097/md.0000000000014792
4. Sosnowski K, Lin F, Chaboyer W, Ranse K, Heffernan AJ, Mitchell M. The effect of the ABCDE/ABCDEF bundle on delirium, functional outcomes, and quality of life in critically ill patients: A systematic review and meta-analysis. International Journal of Nursing Studies. 2022. doi:10.1016/j.ijnurstu.2022.104410
5. Hume NE, Zerfas I, Wong A, et al. Clinical Impact of the Implementation Strategies Used to Apply the 2013 Pain, Agitation/Sedation, Delirium or 2018 Pain, Agitation/Sedation, Delirium, Immobility, Sleep Disruption Guideline Recommendations: A Systematic Review and Meta-Analysis. Critical Care Medicine. 2024. doi:10.1097/ccm.0000000000006178
6. Brown JC, Querubin JA, Ding L, et al. Improving ABCDEF Bundle Compliance and Clinical Outcomes in the ICU: Randomized Control Trial to Assess the Impact of Performance Measurement, Feedback, and Data Literacy Training.. Critical care explorations. 2022. doi:10.1097/CCE.0000000000000679
7. Sosnowski KJ, Ranse KL, Mitchell ML, et al. Effects of the ABCDEF Bundle on Delirium, Function, and Quality of Life in Australian ICU Patients: A Pragmatic Randomized Controlled Trial.. Critical care medicine. 2026. doi:10.1097/CCM.0000000000007154