The prevalence and effects of delirium in very old individuals aged ≥80 years have not yet been systematically evaluated. Therefore, this large single-center study of the one-year prevalence of delirium in 3,076 patients in 27 medical departments of the University Hospital of Zurich was conducted.

Patient scores on the Delirium Observation Screening scale, Intensive Care Delirium Screening Checklist, Diagnostic and Statistical Manual, 5th edition, and electronic Patient Assessment–Acute Care (nursing tool) resulted in the inclusion of 3,076 individuals in 27 departments. The prevalence rates were determined by simple logistic regressions, odds ratios (ORs), and confidence intervals.

Of the 3,076 patients, 1,285 (41.8%) developed delirium. The prevalence rates in the 27 departments ranged from 15% in rheumatology (OR = 0.30) to 73% in intensive care (OR = 5.25). Delirious patients were more likely to have been admitted from long-term care facilities (OR = 2.26) or because of emergencies (OR = 2.24). The length of their hospital stay was twice as long as that for other patients. Some died before discharge (OR = 24.88), and others were discharged to nursing homes (OR = 2.96) or assisted living facilities (OR = 2.2).

This is the largest study to date regarding the prevalence of delirium in patients aged ≥80 years and the medical characteristics of these patients. Almost two out of five patients developed delirium, with a high risk of loss of independence and mortality.

Although age and pre-existent dementia are robust risk factors for developing delirium, evidence for patients older than 90 years is lacking. Therefore, this study assesses the delirium prevalence rates and sequelae in this age group.

Based on a Diagnostic and Statistical Manual (DSM)-5, Delirium Observation screening scale (DOS), and Intensive Care Delirium Screening Checklist (ICDSC) construct, in this prospective cohort study, the prevalence rates and sequelae of delirium were determined in 428 patients older than 90 years by simple logistic regressions and corresponding odds ratios (ORs).

The overall prevalence delirium rate was 45.2%, with a wide range depending upon specialty: intermediate and intensive care services (83.1%), plastic surgery and palliative care (75%), neurology (72%), internal medicine (69%) vs. dermatology (26.5%), and angiology (14.5%). Delirium occurred irrespective of age and gender; however, pre-existent dementia was the strongest delirium predictor (OR 36.05). Delirious patients were less commonly admitted from home (OR 0.47) than from assisted living (OR 2.24), indicating functional impairment. These patients were more severely ill, as indicated by emergency (OR 3.25) vs. elective admission (OR 0.3), requirement for intensive care management (OR 2.12) and ventilation (OR 5.56–8.33). At discharge, one-third did not return home (OR 0.22) and almost half were transferred to assisted living (OR 2.63), or deceased (OR 47.76).

At age older than 90 years, the prevalence and sequelae of delirium are substantial. In particular, functional impairment and pre-existent dementia predicted delirium and subsequently, the loss of independence and death were imminent.

Patients with terminal illness are at high risk of developing delirium, in particular, those with multiple predisposing and precipitating risk factors. Delirium in palliative care is largely under-researched, and few studies have systematically assessed key aspects of delirium in elderly, palliative-care patients.

In this prospective, observational cohort study at a tertiary care center, 229 delirious palliative-care patients stratified by age: <65 (N = 105) and ≥65 years (N = 124), were analyzed with logistic regression models to identify associations with respect to predisposing and precipitating factors.

In 88% of the patients, the underlying diagnosis was cancer. Mortality rate and median time to death did not differ significantly between the two age groups. No inter-group differences were detected with respect to gender, care requirements, length of hospital stay, or medical costs. In patients ≥65 years, exclusively predisposing factors were relevant for delirium, including hearing impairment [odds ratio (OR) 3.64; confidence interval (CI) 1.90–6.99; P < 0.001], hypertension (OR 3.57; CI 1.84–6.92; P < 0.001), and chronic kidney disease (OR 4.84; CI 1.19–19.72; P = 0.028). In contrast, in patients <65 years, only precipitating factors were relevant for delirium, including cerebral edema (OR 0.02; CI 0.01–0.43; P = 0.012).

The results of this study demonstrate that death in delirious palliative-care patients occurs irrespective of age. The multifactorial nature and adverse outcomes of delirium across all age in these patients require clinical recognition. Potentially reversible factors should be detected early to prevent or mitigate delirium and its poor survival outcomes.

The general in-hospital mortality and interrelationship with delirium are vastly understudied. Therefore, this study aimed to assess the rates of in-hospital mortality and terminal delirium.

In this prospective cohort study of 28,860 patients from 37 services including 718 in-hospital deaths, mortality rates and prevalence of terminal delirium were determined with simple logistic regressions and their respective odds ratios (ORs).

Although overall in-hospital mortality was low (2.5%), substantial variance between services became apparent: Across intensive care services the rate was 10.8% with a 5.8-fold increased risk, across medical services rates were 4.4% and 2.4-fold, whereas at the opposite end, across surgical services rates were 0.7% and 87% reduction, respectively. The highest in-hospital mortality rate occurred on the palliative care services (27.3%, OR 19.45). The general prevalence of terminal delirium was 90.7% and ranged from 83.2% to 100%. Only across intensive care services (98.1%, OR 7.48), specifically medical intensive care (98.1%, OR 7.48) and regular medical services (95.8%, OR 4.12) rates of terminal delirium were increased. In contrast, across medical services (86.4%, OR 0.32) and in particular oncology (73.9%, OR 0.25), pulmonology (72%, OR 0.31) and cardiology (63.2%, OR 0.4) rates were decreased. For the remaining services, rates of terminal delirium were the same.

Although in-hospital mortality was low, the interrelationship with delirium was vast: most patients were delirious at the end of life. The implications of terminal delirium merit further studies.

The prevalence rates and adversities of delirium have not yet been systematically evaluated and are based on selected populations, limited sample sizes, and pooled studies. Therefore, this study assesses the prevalence rates and outcome of and odds ratios for managing services for delirium.

In this prospective cohort study, based on the Diagnostic and Statistical Manual (DSM) 5, the Delirium Observation Screening (DOS) scale, and the Intensive Care Delirium Screening Checklist (ICDSC) construct, 28,118 patients from 35 managing services were included, and the prevalence rates and adverse outcomes were determined by simple logistic regressions and their corresponding odds ratios (ORs).

Delirious patients were older, admitted from institutions (OR 3.44–5.2), admitted as emergencies (OR 1.87), hospitalized twice longer, and discharged, transferred to institutions (OR 5.47–6.6) rather than home (OR 0.1), or deceased (OR 43.88). The rate of undiagnosed delirium was 84.2%. The highest prevalence rates were recorded in the intensive care units (47.1–84.2%, pooled 67.9%); in the majority of medical services, rates ranged from 20% to 40% (pooled 26.2%), except, at both ends, palliative care (55.9%), endocrinology (8%), and rheumatology (4.4%). Conversely, in surgery and its related services, prevalence rates were lower (pooled 13.1%), except for cardio- and neurosurgical services (53.3% and 46.4%); the lowest prevalence rate was recorded in obstetrics (2%).

Delirium remains underdiagnosed, and novel screening approaches are required. Furthermore, this study identified the impact of delirium on patients, determined the prevalence rates for 32 services, and elucidated the association between individual services and delirium.

Nursing instruments have the potential for daily screening of delirium; however, they have not yet been evaluated. Therefore, after assessing the functional domains of the electronic Patient Assessment — Acute Care (ePA-AC), this study evaluates the cognitive and associated domains.

In this prospective cohort study in the intensive care unit, 277 patients were assessed and 118 patients were delirious. The impacts of delirium on the cognitive domains, consciousness and cognition, communication and interaction, in addition to respiration, pain, and wounds were determined with simple logistic regressions and their respective odds ratios (ORs).

Delirium was associated with substantial impairment throughout the evaluated domains. Delirious patients were somnolent (OR 6), their orientation (OR 8.2–10.6) and ability to acquire knowledge (OR 5.5–11.6) were substantially impaired, they lost the competence to manage daily routines (OR 8.2–22.4), and their attention was compromised (OR 12.8). In addition, these patients received psychotropics (OR 3.8), were visually impaired (OR 1.8), unable to communicate their needs (OR 5.6–7.6), displayed reduced self-initiated activities (OR 6.5–6.9) and challenging behaviors (OR 6.2), as well as sleep–wake disturbances (OR 2.2–5), Furthermore, delirium was associated with mechanical ventilation, abdominal/thoracic injuries or operations (OR 4.2–4.4), and sensory perception impairment (OR 3.9–5.8).

Delirium caused substantial impairment in cognitive and associated domains. In addition to the previously described functional impairments, these findings will aid the implementation of nursing instruments in delirium screening.

Nursing assessments have been recommended for the daily screening for delirium; however, the utility of individual items have not yet been tested. In a first step in establishing the potential of the electronic Patient Assessment-Acute Care (ePA-AC) as such, the impact of delirium on the functional domains was assessed.

In this prospective observational cohort study, 277 patients were assessed and 118 patients were delirious. The impact of delirium on functional domains of the ePA-AC related to self-initiated activity, nutrition, and elimination was determined with simple logistic regressions.

Patients with delirium were older, sicker, were more commonly sedated during the assessment, stayed longer in the intensive care unit (ICU) and floors, and less commonly discharged home. A general pattern was the loss of abilities and full functioning equivalent to global impairment. For self-initiated mobility, in and out of the bed sizable limitations were noted and substantial inability to transfer caused friction and shearing. Similarly, any exhaustion and fatigue were associated with delirium. For self-initiated grooming and dressing, the impairment was greater in the upper body. Within the nutritional domain, delirium affected self-initiated eating and drinking, the amount of food and fluids, energy and nutrient, as well as parenteral nutrition requirement. In delirious patients, the fluid demand was rather increased than decreased, tube feeding more often required and dysphagia occurred. For the elimination domain, urination was not affected — of note, most patients were catheterized, whereas abilities to initiate or control defecation were affected.

Delirium was associated with sizable impairment in the level of functioning. These impairments could guide supportive interventions for delirious patients and perspectively implement nursing instruments for delirium screening.