Association Between Critical Care Admissions and Cognitive Trajectories in Older Adults

Assessing Risk Factors for Cognitive Decline Using Electronic Health Record Data: A Scoping Review

Background

The data and information contained within electronic health records (EHR) provide a rich, diverse, longitudinal view of real-world patient histories, offering valuable opportunities to study antecedent risk factors for cognitive decline. However, the extent to which such records' data have been utilized to elucidate the risk factors of cognitive decline remains unclear.

Methods

A scoping review was conducted following the PRISMA guideline, examining articles published between January 2010 and April 2023, from PubMed, Web of Science, and CINAHL. Inclusion criteria focused on studies using EHR to investigate risk factors for cognitive decline. Each article was screened by at least two reviewers. Data elements were manually extracted based on a predefined schema. The studied risk factors were classified into categories, and a research gap was identified.

Results

From 1,593 articles identified, 80 were selected. The majority (87.5%) were retrospective cohort studies, with 66.3% using datasets of over 10,000 patients, predominantly from the US or UK. Analysis showed that 48.8% of studies addressed medical conditions, 31.3% focused on medical interventions, and 17.5% on lifestyle, socioeconomic status, and environmental factors. Most studies on medical conditions were linked to an increased risk of cognitive decline, whereas medical interventions addressing these conditions often reduced the risk.

Conclusions

EHR data significantly enhanced our understanding of medical conditions, interventions, lifestyle, socioeconomic status, and environmental factors related to the risk of cognitive decline.

Cognitive impairment in critically ill patients and former critically ill patients: A concept analysis

OBJECTIVES

This concept analysis aimed to clarify the meaning of the concept of cognitive impairment in critically ill patients throughout the trajectory of their rehabilitation during and after an intensive care unit admission.

REVIEW METHODS USED

This study used concept analysis based on Rodgers' evolutionary method.

DATA SOURCES

A systematic search was conducted in Cumulative Index to Nursing and Allied Health Literature, Public MEDLINE, and American Psychological Associations PsycINFO. The web was searched for grey literature.

REVIEW METHODS

Overall search terms used were "patients with cognitive impairments" AND "intensive care unit". Literature published between 2008 and 2022 was included and screened by title and abstract using systematic review software. The descriptive analysis focussed on surrogate terms/related concepts, attributes, and contextual basis.

RESULTS

Thirty studies were included, representing variability in study design and country of origin. The analysis uncovered descriptions of the general terminology and the temporal trajectory of the concept, spanning from the acute phase to a long-term perspective. Attributes of the concept were described as delirium and domains of cognition. Antecedents were juxtaposed to risk factors, which were multifactorial. Consequences of cognitive impairment related to patients' quality of life, such as a decline in their ability to function independently, return to work, and manage everyday life. Also, cognitive impairment was identified as a significant public health problem.

CONCLUSION

Cognitive impairment is a complex concept with many surrogate and related terms. Furthermore, the concept is inextricably intertwined with the concepts of delirium and post-intensive care syndrome. Cognitive impairment may manifest as symptoms that can be challenging to identify and assess due to limitations in current screening tools and the absence of a consensus on timing. In relation to assessment and preventive strategies, the findings underline the need to distinguish between acute and long-term cognitive impairment.

REGISTRATION

There is no study registration number.

Objective and subjective cognition in survivors of COVID-19 one year after ICU discharge: the role of demographic, clinical, and emotional factors

BACKGROUND

Intensive Care Unit (ICU) COVID-19 survivors may present long-term cognitive and emotional difficulties after hospital discharge. This study aims to characterize the neuropsychological dysfunction of COVID-19 survivors 12 months after ICU discharge, and to study whether the use of a measure of perceived cognitive deficit allows the detection of objective cognitive impairment. We also explore the relationship between demographic, clinical and emotional factors, and both objective and subjective cognitive deficits.

METHODS

Critically ill COVID-19 survivors from two medical ICUs underwent cognitive and emotional assessment one year after discharge. The perception of cognitive deficit and emotional state was screened through self-rated questionnaires (Perceived Deficits Questionnaire, Hospital Anxiety and Depression Scale and Davidson Trauma Scale), and a comprehensive neuropsychological evaluation was carried out. Demographic and clinical data from ICU admission were collected retrospectively.

RESULTS

Out of eighty participants included in the final analysis, 31.3% were women, 61.3% received mechanical ventilation and the median age of patients was 60.73 years. Objective cognitive impairment was observed in 30% of COVID-19 survivors. The worst performance was detected in executive functions, processing speed and recognition memory. Almost one in three patients manifested cognitive complaints, and 22.5%, 26.3% and 27.5% reported anxiety, depression and post-traumatic stress disorder (PTSD) symptoms, respectively. No significant differences were found in the perception of cognitive deficit between patients with and without objective cognitive impairment. Gender and PTSD symptomatology were significantly associated with perceived cognitive deficit, and cognitive reserve with objective cognitive impairment.

CONCLUSIONS

One-third of COVID-19 survivors suffered objective cognitive impairment with a frontal-subcortical dysfunction 12 months after ICU discharge. Emotional disturbances and perceived cognitive deficits were common. Female gender and PTSD symptoms emerged as predictive factors for perceiving worse cognitive performance. Cognitive reserve emerged as a protective factor for objective cognitive functioning.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04422444; June 9, 2021.

The Two-Way Route between Delirium Disorder and Dementia: Insights from COVID-19

BACKGROUND

Delirium disorder is a frequent neurological complication of SARS-CoV-2 infection and associated with increased disease severity and mortality. Cognitive impairment is a major risk factor for developing delirium disorder during COVID-19, which, in turn, increases the risk of subsequent neurological complications and cognitive decline.

SUMMARY

The bidirectional connection between delirium disorder and dementia likely resides at multiple levels, and its pathophysiological mechanisms during COVID-19 include endothelial damage, blood-brain barrier dysfunction, and local inflammation, with activation of microglia and astrocytes. Here, we describe the putative pathogenic pathways underlying delirium disorder during COVID-19 and highlight how they cross with the ones leading to neurodegenerative dementia.

KEY MESSAGES

The analysis of the two-sided link can offer useful insights for confronting with long-term neurological consequences of COVID-19 and framing future prevention and early treatment strategies.

Instruments Assessing Cognitive Impairment in Survivors of Critical Illness and Reporting of Race Norms: A Systematic Review

To conduct a systematic review to summarize cognitive instruments being used in long-term outcome studies of survivors of adult critical illness, as well as evaluate whether these measures are reported as using patient demographic norms, specifically race norms.

DATA SOURCES

A comprehensive search was conducted in PubMed (National Center for Biotechnology Information), Excerpta Medica dataBASE (Ovid), Psychological Information Database (ProQuest), and Web of Science (Clarivate) for English language studies published since 2002.

STUDY SELECTION

Studies were eligible if the population included adult ICU survivors assessed for postdischarge cognitive outcomes.

DATA EXTRACTION

Two independent reviewers screened abstracts, examined full text, and extracted data from all eligible articles.

DATA SYNTHESIS

A total of 98 articles (55 unique cohorts: 22 general ICU, 14 Acute respiratory distress syndrome/Acute respiratory failure/Sepsis, 19 COVID-19 and other subpopulations) were eligible for data extraction and synthesis. Among general ICU survivors, the majority of studies (n = 15, 68%) assessed cognition using multiple instruments, of which the most common was the Mini-Mental State Examination. Only nine of the 22 studies (41%) explicitly reported using patient demographic norms for scoring neuropsychological cognitive tests. Of the nine, all reported using age as a norming characteristic, education was reported in eight (89%), sex/gender was reported in five (55%), and race/ethnicity was reported in three (33%). Among Acute respiratory distress syndrome/Acute respiratory failure/Sepsis survivors, norming characteristics were reported in only four (28%) of the 14 studies, of which all reported using age and none reported using race/ethnicity.

CONCLUSIONS

Less than half of the studies measuring cognitive outcomes in ICU survivors reported the use of norming characteristics. There is substantial heterogeneity in how studies reported the use of cognitive instruments, and hence, the prevalence of the use of patient norms may be underestimated. These findings are important in the development of appropriate standards for use and reporting of neuropsychological tests among ICU survivors.

Virtual Reality-Based Early Neurocognitive Stimulation in Critically Ill Patients: A Pilot Randomized Clinical Trial

This study focuses on the application of a non-immersive virtual reality (VR)-based neurocognitive intervention in critically ill patients. Our aim was to assess the feasibility of direct outcome measures to detect the impact of this digital therapy on patients’ cognitive and emotional outcomes. Seventy-two mechanically ventilated adult patients were randomly assigned to the “treatment as usual” (TAU, n = 38) or the “early neurocognitive stimulation” (ENRIC, n = 34) groups. All patients received standard intensive care unit (ICU) care. Patients in the ENRIC group also received adjuvant neurocognitive stimulation during the ICU stay. Outcome measures were a full neuropsychological battery and two mental health questionnaires. A total of 42 patients (21 ENRIC) completed assessment one month after ICU discharge, and 24 (10 ENRIC) one year later. At one-month follow-up, ENRIC patients had better working memory scores (p = 0.009, d = 0.363) and showed up to 50% less non-specific anxiety (11.8% vs. 21.1%) and depression (5.9% vs. 10.5%) than TAU patients. A general linear model of repeated measures reported a main effect of group, but not of time or group–time interaction, on working memory, with ENRIC patients outperforming TAU patients (p = 0.008, η_p² = 0.282). Our results suggest that non-immersive VR-based neurocognitive stimulation may help improve short-term working memory outcomes in survivors of critical illness. Moreover, this advantage could be maintained in the long term. An efficacy trial in a larger sample of participants is feasible and must be conducted.

Identifying cues of distorted memories in intensive care by focus group interview of nurses

AIM

To determine cues to identify intensive care unit patients with distorted memories and related practices.

DESIGN

Qualitative descriptive study.

METHODS

Twenty nurses were included in semi-structured focus groups. Qualitative content analysis was conducted.

RESULTS

Cues and nursing practices related to distorted memories emerged under the following categories: "Get to know daily life before admission," "Facial expressions and behaviour are different from usual," "Pay close attention to the treatment outcome," "Notice it after the fact," "Sharing patients' intensive care unit experiences" and "Creates a new life." Nurses tried to detect distorted memories by observing the patients' facial expressions, medication effects and delirium presence during their normal lives and treatments, while trying to understand the patients' intensive care unit experiences and provide care that promotes autonomous living. This study emphasizes the importance of support for reconstructing ordinary life through communication and rehabilitation, in addition to support for medical care for distorted memories.

Delirium and long term cognition in critically ill patients

Delirium, a form of acute brain dysfunction, is very common in the critically ill adult patient population. Although its pathophysiology is poorly understood, multiple factors associated with delirium have been identified, many of which are coincident with critical illness. To date, no drug or non-drug treatments have been shown to improve outcomes in patients with delirium. Clinical trials have provided a limited understanding of the contributions of multiple triggers and processes of intensive care unit (ICU) acquired delirium, making identification of therapies difficult. Delirium is independently associated with poor long term outcomes, including persistent cognitive impairment. A longer duration of delirium is associated with worse long term cognition after adjustment for age, education, pre-existing cognitive function, severity of illness, and exposure to sedatives. Interestingly, differences in prevalence are seen between ICU survivor populations, with survivors of acute respiratory distress syndrome experiencing higher rates of cognitive impairment at early follow-up compared with mixed ICU survivor populations. Although cognitive performance improves over time for some ICU survivors, impairment is persistent in others. Studies have so far been unable to identify patients at higher risk of long term cognitive impairment; this is an active area of scientific investigation.

Association of Hospitalization with Long-Term Cognitive Trajectories in Older Adults

IMPORTANCE

Hospitalizations are associated with cognitive decline in older adults.

OBJECTIVE

To determine the association between hospitalization characteristics and the trajectory of cognitive function in older adults.

DESIGN

Population-based longitudinal study of cognitive aging.

SETTING

Olmsted Medical Center and Mayo Clinic, the only centers in Olmsted County, Minnesota, with hospitalization capacity.

PARTICIPANTS

Individuals without dementia at baseline, with consecutive cognitive assessments from 2004 through 2017, and at least one visit after the age of 60.

MEASUREMENTS

The primary outcome was longitudinal changes in global cognitive z-score. Secondary outcomes were changes in four cognitive domains: memory, attention/executive function, language, and visuospatial skills. Hospitalization characteristics analyzed included elective versus nonelective, medical versus surgical, critical care versus no critical care admission, and long versus short duration admissions.

RESULTS

Of 4,587 participants, 1,622 had 1 and more hospital admission. Before hospitalization, the average slope of the global z-score was -0.031 units/year. After hospitalization, the rate of annual global z-score accelerated by -0.051 (95% CI = -0.057, -0.045) units, P < .001, resulting in an estimated annual slope after the first hospitalization of -0.082. The accelerated decline was found in all four cognitive domains (memory, visuospatial, language, and executive, all P < .001). The acceleration of the decline in global z-score following hospitalization was greater for medical compared to surgical hospitalizations (slope change following hospitalization = -0.064 vs -0.034 for medical vs surgical, P < .001), and nonelective compared to elective admissions (slope change following hospitalization = -0.075 vs -0.037 for nonelective vs elective, P < .001). The acceleration of cognitive decline was not different for hospitalization with intensive care unit admission versus not.

CONCLUSIONS

Hospitalization of older adults is associated with accelerated decline of global and domain-specific cognitive domains, with the rate of decline dependent upon type of admission. The clinical impact of this accelerated decline will depend on the individual's baseline cognitive reserve and expected longevity.

Daytime-to-Nighttime Sleep Ratios and Cognitive Impairment in Older Intensive Care Unit Survivors

BACKGROUND

Sleep duration and proportion of daytime versus nighttime sleep may affect cognitive function in older patients in the transition out of the intensive care unit.

OBJECTIVE

To explore the relationship between the daytime-to-nighttime sleep ratio and cognitive impairment in older intensive care unit survivors.

METHODS

The study enrolled 30 older adults within 24 to 48 hours after intensive care unit discharge. All participants were functionally independent before admission and underwent mechanical ventilation in the intensive care unit. Actigraphy was used to estimate daytime (6 AM to 9:59 PM) and nighttime (10 PM to 5:59 AM) total sleep duration. Daytime-to-nighttime sleep ratios were calculated by dividing the proportion of daytime sleep by the proportion of nighttime sleep. The National Institutes of Health Toolbox Cognition Battery Dimensional Change Card Sort Test (DCCST) was used to assess cognition. Associations between sleep and cognition were explored using multivariate regression after adjusting for covariates.

RESULTS

The mean (SD) daytime sleep duration was 7.55 (4.30) hours (range, 0.16-14.21 hours), and the mean (SD) nighttime sleep duration was 4.99 (1.95) hours (range, 0.36-7.21 hours). The mean (SD) daytime-to-nighttime sleep ratio was 0.71 (0.30) (range, 0.03-1.10). Greater daytime sleep duration (β = -0.351, P = .008) and higher daytime-to-nighttime sleep ratios (β = -0.373, P = .008) were negatively associated with DCCST scores.

CONCLUSIONS

The daytime-to-nighttime sleep ratio was abnormally high in the study population, revealing an altered sleep/wake cycle. Higher daytime-to-nighttime sleep ratios were associated with worse cognition, suggesting that proportionally greater daytime sleep may predict cognitive impairment.

Family automated voice reorientation (FAVoR) intervention for mechanically ventilated patients in the intensive care unit: Study protocol for a randomized controlled trial

Delirium in the intensive care unit (ICU) affects up to 80% of critically ill, mechanically ventilated (MV) adults. Delirium is associated with substantial negative outcomes, including increased hospital complications and long-term effects on cognition and health status in ICU survivors. The purpose of this randomized controlled trial is to test the effectiveness of a Family Automated Voice Reorientation (FAVoR) intervention on delirium among critically ill MV patients. The FAVoR intervention uses scripted audio messages, which are recorded by the patient's family and played at hourly intervals during daytime hours. This ongoing orientation to the ICU environment through recorded messages in a voice familiar to the patient may enable the patient to more accurately interpret the environment and thus reduce risk of delirium. The study's primary aim is to test the effect of the FAVoR intervention on delirium in critically ill MV adults in the ICU. The secondary aims are to explore: (1) if the effect of FAVoR on delirium is mediated by sleep, (2) if selected biobehavioral factors moderate the effects of FAVoR on delirium, and (3) the effects of FAVoR on short-term and long-term outcomes, including cognition and health status. Subjects (n = 178) are randomly assigned to the intervention or control group within 48 h of initial ICU admission and intubation. The intervention group receives FAVoR over a 5-day period, while the control group receives usual care. Delirium-free days, sleep and activity, cognition, patient-reported health status and sleep quality, and data regarding iatrogenic/environmental and biobehavioral factors are collected.

Brain MRI after critical care admission: A longitudinal imaging study

PURPOSE

To investigate the association between episodes of critical care hospitalizations and delirium with structural brain changes in older adults.

MATERIALS AND METHODS

We included Mayo Clinic Study of Aging participants ≥60 years old at the time of study enrollment (October 29, 2004, through September 11, 2017) with available brain MRI and 'amyloid' positron emission tomography (PET) scans. We tested the hypothesis that a) intensive care unit (ICU) admission is associated with greater cortical thinning and atrophy in entorhinal cortex, inferior temporal cortex, middle temporal cortex, and fusiform cortex (Alzheimer''s disease-signature regions); b) atrophy in hippocampus and corpus callosum; c) delirium accelerates these changes; and d) ICU admission is not associated with increased deposition of cortical amyloid.

RESULTS

ICU admission was associated with cortical thinning in temporal, frontal, and parietal cortices, and decreases in hippocampal/corpus callosum volumes, but not Alzheimer''s disease-signature regions. For hippocampal volume, and 10 of 14 cortical thickness measurements, the change following ICU admission was significantly more pronounced for those who experienced delirium. ICU admission was not associated with an increased amyloid burden.

CONCLUSIONS

Critical care hospitalization is associated with accelerated brain atrophy in selected brain regions, without increases in amyloid deposition, suggesting a pathogenesis based on neurodegeneration unrelated to Alzheimer''s pathway.

Executive Function, Dexterity, and Discharge Disposition in Older Intensive Care Unit Survivors

BACKGROUND

Dexterity is a component of motor function. Executive function, a subdomain of cognition, may affect dexterity in older adults recovering from critical illness after discharge from an intensive care unit (ICU).

OBJECTIVES

To explore associations between executive function (attention and cognitive flexibility) and dexterity (fine motor coordination) in the early post-ICU period and examine dexterity by acuity of discharge disposition.

METHODS

The study involved 30 older adults who were functionally independent before hospitalization, underwent mechanical ventilation in the ICU, and had been discharged from the ICU 24 to 48 hours previously. Dexterity was evaluated with the National Institutes of Health Toolbox (NIHTB) Motor Battery 9-Hole Pegboard Dexterity Test (PDT); attention, with the NIHTB Cognition Battery Flanker Inhibitory Control and Attention Test (FICAT); and cognitive flexibility, with the NIHTB Cognition Battery Dimensional Change Card Sort Test (DCCST). Exploratory regression was used to examine associations between executive function and dexterity (fully corrected T scores). Independent-samples t tests were used to compare dexterity between participants discharged home and those discharged to a facility.

RESULTS

FICAT (β = 0.375, P = .03) and DCCST (β = 0.698, P = .001) scores were independently and positively associated with PDT scores. Further, PDT scores were worse among participants discharged to a facility than among those discharged home (mean [SD], 26.71 [6.14] vs 36.33 [10.30]; t24 = 3.003; P = .006).

CONCLUSIONS

Poor executive function is associated with worse dexterity; thus, dexterity may be a correlate of both post-ICU cognitive impairment and functional decline. Performance on dexterity tests could identify frail older ICU survivors at risk for worse discharge outcomes.

Cognitive phenotypes 1 month after ICU discharge in mechanically ventilated patients: a prospective observational cohort study

BACKGROUND

ICU patients undergoing invasive mechanical ventilation experience cognitive decline associated with their critical illness and its management. The early detection of different cognitive phenotypes might reveal the involvement of diverse pathophysiological mechanisms and help to clarify the role of the precipitating and predisposing factors. Our main objective is to identify cognitive phenotypes in critically ill survivors 1 month after ICU discharge using an unsupervised machine learning method, and to contrast them with the classical approach of cognitive impairment assessment. For descriptive purposes, precipitating and predisposing factors for cognitive impairment were explored.

METHODS

A total of 156 mechanically ventilated critically ill patients from two medical/surgical ICUs were prospectively studied. Patients with previous cognitive impairment, neurological or psychiatric diagnosis were excluded. Clinical variables were registered during ICU stay, and 100 patients were cognitively assessed 1 month after ICU discharge. The unsupervised machine learning K-means clustering algorithm was applied to detect cognitive phenotypes. Exploratory analyses were used to study precipitating and predisposing factors for cognitive impairment.

RESULTS

K-means testing identified three clusters (K) of patients with different cognitive phenotypes: K1 (n = 13), severe cognitive impairment in speed of processing (92%) and executive function (85%); K2 (n = 33), moderate-to-severe deficits in learning-memory (55%), memory retrieval (67%), speed of processing (36.4%) and executive function (33.3%); and K3 (n = 46), normal cognitive profile in 89% of patients. Using the classical approach, moderate-to-severe cognitive decline was recorded in 47% of patients, while the K-means method accurately classified 85.9%. The descriptive analysis showed significant differences in days (p = 0.016) and doses (p = 0.039) with opioid treatment in K1 vs. K2 and K3. In K2, there were more women, patients were older and had more comorbidities (p = 0.001) than in K1 or K3. Cognitive reserve was significantly (p = 0.001) higher in K3 than in K1 or K2.

CONCLUSION

One month after ICU discharge, three groups of patients with different cognitive phenotypes were identified through an unsupervised machine learning method. This novel approach improved the classical classification of cognitive impairment in ICU survivors. In the exploratory analysis, gender, age and the level of cognitive reserve emerged as relevant predisposing factors for cognitive impairment in ICU patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier:NCT02390024; March 17,2015.

Is hospitalisation a risk factor for cognitive decline in the elderly?

PURPOSE OF REVIEW

Cognitive decline is frequently reported after hospitalisation in the contexts of surgery, delirium and critical care. The question not adequately addressed is whether all types of acute hospitalisations increase the risk of cognitive decline. As acute hospitalisations are common in the elderly, who are also vulnerable to cognitive decline, this possible association is of significant concern.

RECENT FINDINGS

This review summarises cognitive outcomes from recent observational studies investigating acute hospitalisation (emergent and elective) in older age adults. Studies were identified from searching Medline, Embase and PsycINFO databases and citations lists. The highest incidence of cognitive decline has been reported following critical care admissions and admissions complicated by delirium, although all types of acute hospitalisations are implicated. Age is the most consistent risk factor for cognitive decline. Several etiological and therapeutic aspects are being investigated, particularly the measurement of inflammatory biomarkers and treatment with anti-inflammatory medications.

SUMMARY

Acute hospitalisation for any reason appears to increase the risk of cognitive decline in older adults, but the cause remains elusive. Future research must clarify the nature and modifiers of posthospitalisation cognitive change, a priority in the face of an ageing population.

Cut-Off Values of the Post-Intensive Care Syndrome Questionnaire for the Screening of Unplanned Hospital Readmission within One Year

PURPOSE

This study aimed to assign weights for subscales and items of the Post-Intensive Care Syndrome questionnaire and suggest optimal cut-off values for screening unplanned hospital readmissions of critical care survivors.

METHODS

Seventeen experts participated in an analytic hierarchy process for weight assignment. Participants for cut-off analysis were 240 survivors who had been admitted to intensive care units for more than 48 hours in three cities in Korea. We assessed participants using the 18-item Post-Intensive Care Syndrome questionnaire, generated receiver operating characteristic curves, and analysed cut-off values for unplanned readmission based on sensitivity, specificity, and positive likelihood ratios.

RESULTS

Cognitive, physical, and mental subscale weights were 1.13, 0.95, and 0.92, respectively. Incidence of unplanned readmission was 25.4%. Optimal cut-off values were 23.00 for raw scores and 23.73 for weighted scores (total score 54.00), with an area of under the curve (AUC) of .933 and .929, respectively. There was no significant difference in accuracy for original and weighted scores.

CONCLUSION

The optimal cut-off value accuracy is excellent for screening of unplanned readmissions. We recommend that nurses use the Post-Intensive Care Syndrome Questionnaire to screen for readmission risk or evaluating relevant interventions for critical care survivors.