Debating the Role of Arousal in Delirium Diagnosis: Should Delirium Diagnosis Be Inclusive or Restrictive?

Advancing specificity in delirium: The delirium subtyping initiative

BACKGROUND

Delirium, a common syndrome with heterogeneous etiologies and clinical presentations, is associated with poor long-term outcomes. Recording and analyzing all delirium equally could be hindering the field's understanding of pathophysiology and identification of targeted treatments. Current delirium subtyping methods reflect clinically evident features but likely do not account for underlying biology.

METHODS

The Delirium Subtyping Initiative (DSI) held three sessions with an international panel of 25 experts.

RESULTS

Meeting participants suggest further characterization of delirium features to complement the existing Diagnostic and Statistical Manual of Mental Disorders Fifth Edition Text Revision diagnostic criteria. These should span the range of delirium-spectrum syndromes and be measured consistently across studies. Clinical features should be recorded in conjunction with biospecimen collection, where feasible, in a standardized way, to determine temporal associations of biology coincident with clinical fluctuations.

DISCUSSION

The DSI made recommendations spanning the breadth of delirium research including clinical features, study planning, data collection, and data analysis for characterization of candidate delirium subtypes.

HIGHLIGHTS

Delirium features must be clearly defined, standardized, and operationalized. Large datasets incorporating both clinical and biomarker variables should be analyzed together. Delirium screening should incorporate communication and reasoning.

The phenotype of delirium based on a close reading of diagnostic criteria

OBJECTIVE

Although delirium is well known to acute care clinicians, the features required for its diagnosis and how to understand and operationalize them remain sticking points in the field. To clarify the delirium phenotype, we present a close reading of past and current sets of delirium diagnostic criteria.

METHODS

We first differentiate the delirium syndrome (i.e., features evaluated at bedside) from additional criteria required for diagnosis. Next, we align related features across diagnostic systems and examine them in context to determine intent. Where criteria are ambiguous, we review common delirium instruments to illustrate how they have been interpreted.

RESULTS

An acute disturbance in attention is universally attested across diagnostic systems. A second core feature denotes confusion and has been included across systems as disturbance in awareness, impaired consciousness, and thought disorganization. This feature may be better understood as a disturbance in thought clarity and operationalized in terms of neuropsychological domains thereby clearly linking it to global neurocognitive disturbance. Altered level of activity describes a third core feature, including motor and sleep/wake cycle disturbances. Excluding stupor (wherein mental content cannot be assessed due to reduced arousal) from delirium, as in DSM-5-TR, is appropriate for a psychiatric diagnosis, but the brain injury exclusion in ICD-11 is unjustified.

CONCLUSIONS

The delirium phenotype involves a disturbance in attention, qualitative thought clarity, and quantitative activity level, including in relation to expected sleep/wake cycles. Future diagnostic systems should include a severity threshold and specify that delirium diagnosis refers to a 24-h period.

Delirium disorder: Unity in diversity

OBJECTIVE

The first objective of this review is to explore the factors that have led to and maintain the division between delirium and acute encephalopathy. The second is to explore the value of harmonizing them through the model of delirium disorder.

METHOD

This narrative review outlines major distinctions between delirium and acute encephalopathy. It also compares them with the model of delirium disorder, which seeks not only to integrate them but also to offer a broader palette of treatment targets.

RESULTS

Delirium implies an underlying acute encephalopathy, whereas acute encephalopathy presents as a spectrum from subsyndromal delirium to coma. Key factors that differentiate these two models include tradition, nuances of the models themselves, linguistic connotations, evoked responses from clinicians, implications of preventability and responsibility, cultural perceptions of non-pharmacological vs pharmacological interventions and economic incentives. A validated set of pathophysiological subtypes may ultimately help link the delirium-spectrum phenotype with various acute encephalopathies.

CONCLUSIONS

Developing a coherent clinical and scientific approach to this set of conditions demands that we first develop a coherent understanding of the conditions themselves and how they relate to one another. Such an approach must embrace the tension between a convergent phenotype and its diverse biological underpinnings.

Divergent: Age, Frailty, and Atypical Presentations of COVID-19 in Hospitalized Patients

Background

Although frailty has been associated with atypical manifestations of infections, little is known about COVID-19 presentations in hospitalized frail patients. We aimed to investigate the association between age, frailty, and clinical characteristics of COVID-19 in hospitalized middle-aged and older adults.

Methods

Longitudinal observational study comprising 711 patients aged ≥50 years consecutively admitted to a university hospital dedicated to COVID-19 severe cases, between March and May 2020. We reviewed electronic medical records to collect data on demographics, comorbidities, COVID-19 signs/symptoms, and laboratory findings on admission. We defined frailty using the Clinical Frailty Scale (CFS=1-9; frail ≥5). We also documented in-hospital mortality. We used logistic regressions to explore associations between age, frailty, and COVID-19 signs/symptoms; and between typical symptoms (fever, cough, dyspnea) and mortality.

Results

Participants had a mean age of 66±11 years, and 43% were female. Overall, 25% were frail, and 37% died. The most common COVID-19 presentations were dyspnea (79%), cough (74%), and fever (62%), but patients aged ≥65 years were less likely to have a co-occurrence of typical symptoms, both in the absence (OR=0.56; 95%CI=0.39-0.79) and in the presence of frailty (OR=0.52; 95%CI=0.34-0.81). In contrast, older age and frailty were associated with unspecific presentations, including functional decline, acute mental change, and hypotension. After adjusting for age, sex, and frailty, reporting fever was associated with lower odds of mortality (OR=0.70; 95%CI=0.50-0.97).

Conclusions

Atypical COVID-19 presentations are common in frail and older hospitalized patients. Providers should be aware of unspecific disease manifestations during the management and follow-up of this population.

Consciousness and the rabbit holes of delirium

Delirium is a common disorder in hospitalized older adults and the defining characteristic is a disturbance of consciousness. Unfortunately, there are currently no testable measures of consciousness as pertains to its disruption in delirium. Not surprisingly rates of recognition of delirium suffer. Arguably, a greater understanding of the quantum of consciousness may improve delirium diagnosis through better diagnostic tools. Candidate dimensions of consciousness derived from fields of psychology, psychiatry, and philosophy are discussed and relevance to delirium explored. Based upon existing literature in the field of consciousness we identify the pre-reflective state, experiential awareness, and functional networks as candidate sites that may be affected in delirium. Opportunities for clinical instrument development and how these tools can be tested are discussed. We conclude that consciousness content may not hold to a unitary measurement, but facets of its integrity that are impacted in delirium are open to further exploration. Disorders in pre-reflective status, experiential awareness, and functional networks may represent the measurable "rabbit holes" of consciousness disturbance.

Delirium disorder

Objective

As the US population ages and with no definitive delirium treatments on the horizon, the delirium epidemic is on course to expand over the coming decades. Recognizing the import of this condition, a recent position statement from 10 medical societies—among whom the American Academy of Neurology was represented—issued recommendations on preferred nomenclature of delirium and acute encephalopathy: it concluded by preferring both terms. Urgently needed is an integrated model that addresses the near-total segregation of these separate bodies of literature, ideally one that offers an interdisciplinary framework to bring these 2 terms and those who use them together.

Methods

We review the historical forces that have led these terms to diverge and consider the unique benefits of each approach as well as their liabilities when considered in isolation. We then explore the potential implications of integrating these concepts and propose a hybrid model to capitalize on the strengths of both the model of delirium and that of acute encephalopathy.

Results

The model we propose—delirium disorder—builds on the recommendations of this recent position statement and provides a unifying framework designed to have clinical utility and interdisciplinary appeal. It also broadens the translational landscape by identifying 4 distinct treatment targets: underlying causes, procognitive factors, delirium (phenotype alone), and neurophysiologic targets.

Conclusions

This person-centered model aims to integrate delirium and acute encephalopathy within a single framework and shared nomenclature. It is hoped that this model aids in harmonizing research efforts and advancing clinical practice.

Association Between Level of Arousal and 30-Day Survival in Acutely Ill Older Adults

OBJECTIVE

To investigate the association between impaired arousal on admission and 30-day mortality in acutely ill older adults.

DESIGN

Retrospective cohort study.

SETTING AND PARTICIPANTS

Patients age +65 years admitted to the geriatric ward of a tertiary university hospital from 2010 to 2018 in Sao Paulo, Brazil.

METHODS

Participants were evaluated on admission according to a standardized comprehensive geriatric assessment model. Delirium was detected using the short version of the Confusion Assessment Method (Short-CAM). We used 2 alternative criteria to define impaired arousal: lethargy, stupor, or coma according to the Short-CAM; and a Glasgow Coma Scale (GCS) score of ≤13. Our primary outcome was time-to-death in 30 days, and we used Cox proportional hazards models to explore the association between impaired arousal and decreased survival.

RESULTS

We included 1554 admissions with a mean age of 81 years and of whom 61% were women. Overall, prevalent delirium was observed in 28% of the cases. We found that in 33% of admissions, patients were lethargic, stuporous, or comatose, and that in 23%, they had GCS scores of ≤13. General 30-day mortality was 19% but reached 32% in patients with GCS scores of ≤13. Impaired arousal was independently associated with lower survival in 30 days, both when defined using Short-CAM criteria [lethargy + stupor + coma: hazard ratio (HR) 2.33, 95% confidence interval (CI) 1.66‒3.27] and GCS scores (GCS 12‒13: HR 1.62, 95% CI 1.13‒2.33; GCS ≤ 11: HR 2.53, 95% CI 1.68‒3.80). In interaction analyses, we confirmed our results in patients who had impaired arousal but were neither delirious (lethargy + stupor + coma: HR 2.16, 95% CI 1.44‒3.24; GCS ≤ 11: HR 3.07; 95% CI 1.50‒6.29) nor demented (lethargy + stupor + coma: HR 1.95, 95% CI 1.15‒3.28).

CONCLUSIONS AND IMPLICATIONS

Level of arousal on admission was an independent predictor of 30-day survival in acutely ill older adults, regardless of delirium or baseline dementia. Clinicians should be aware that even if unsure of whether a patient has delirium, arousal assessment can provide crucial clinical and prognostic insight.