Unravelling the pathophysiology of delirium: a focus on the role of aberrant stress responses

Pathophysiological and behavioral effects of systemic inflammation in aged and diseased rodents with relevance to delirium: A systematic review

Delirium is a frequent outcome for aged and demented patients that suffer a systemic inflammatory insult. Animal models that reconstruct these etiological processes have potential to provide a better understanding of the pathophysiology of delirium. Therefore, we systematically reviewed animal studies in which systemic inflammation was superimposed on aged or diseased animal models. In total, 77 studies were identified. Aged animals were challenged with a bacterial endotoxin in 29 studies, 25 studies superimposed surgery on aged animals, and in 6 studies a bacterial infection, Escherichia coli (E. coli), was used. Diseased animals were challenged with a bacterial endotoxin in 15 studies, two studies examined effects of the cytokine IL-1β, and one study used polyinosinic:polycytidilic acid (poly I:C). This systematic review analyzed the impact of systemic inflammation on the production of inflammatory and neurotoxic mediators in peripheral blood, cerebrospinal fluid (CSF), and on the central nervous system (CNS). Moreover, concomitant behavioral and cognitive symptoms were also evaluated. Finally, outcomes of behavioral and cognitive tests from animal studies were compared to features and symptoms present in delirious patients.

Delirium in critically ill patients

Delirium is common in critically ill patients and associated with increased length of stay in the intensive care unit (ICU) and long-term cognitive impairment. The pathophysiology of delirium has been explained by neuroinflammation, an aberrant stress response, neurotransmitter imbalances, and neuronal network alterations. Delirium develops mostly in vulnerable patients (e.g., elderly and cognitively impaired) in the throes of a critical illness. Delirium is by definition due to an underlying condition and can be identified at ICU admission using prediction models. Treatment of delirium can be improved with frequent monitoring, as early detection and subsequent treatment of the underlying condition can improve outcome. Cautious use or avoidance of benzodiazepines may reduce the likelihood of developing delirium. Nonpharmacologic strategies with early mobilization, reducing causes for sleep deprivation, and reorientation measures may be effective in the prevention of delirium. Antipsychotics are effective in treating hallucinations and agitation, but do not reduce the duration of delirium. Combined pain, agitation, and delirium protocols seem to improve the outcome of critically ill patients and may reduce delirium incidence.

Baseline acetylcholinesterase activity and serotonin plasma levels are not associated with delirium in critically ill patients

Objective

The aim of this study was to investigate whether plasma serotonin levels or acetylcholinesterase activities determined upon intensive care unit admission could predict the occurrence of acute brain dysfunction in intensive care unit patients.

Methods

A prospective cohort study was conducted with a sample of 77 non-consecutive patients observed between May 2009 and September 2010. Delirium was determined using the Confusion Assessment Method for the Intensive Care Unit tool, and the acetylcholinesterase and serotonin measurements were determined from blood samples collected up to a maximum of 24 h after the admission of the patient to the intensive care unit.

Results

In the present study, 38 (49.6%) patients developed delirium during their intensive care unit stays. Neither serum acetylcholinesterase activity nor serotonin level was independently associated with delirium. No significant correlations of acetylcholinesterase activity or serotonin level with delirium/coma-free days were observed, but in the patients who developed delirium, there was a strong negative correlation between the acetylcholinesterase level and the number of delirium/coma-free days, indicating that higher acetylcholinesterase levels are associated with fewer days alive without delirium or coma. No associations were found between the biomarkers and mortality.

Conclusions

Neither serum acetylcholinesterase activity nor serotonin level was associated with delirium or acute brain dysfunction in critically ill patients. Sepsis did not modify these relationships.

Risk factors for incident delirium in an acute general medical setting: a retrospective case-control study

AIMS AND OBJECTIVES

To determine predisposing and precipitating risk factors for incident delirium in medical patients during an acute hospital admission.

BACKGROUND

Incident delirium is the most common complication of hospital admission for older patients. Up to 30% of hospitalised medical patients experience incident delirium. Determining risk factors for delirium is important for identifying patients who are most susceptible to incident delirium.

DESIGN

Retrospective case-control study with two controls per case.

METHODS

An audit tool was used to review medical records of patients admitted to acute medical units for data regarding potential risk factors for delirium. Data were collected between August 2013 and March 2014 at three hospital sites of a healthcare organisation in Melbourne, Australia. Cases were 161 patients admitted to an acute medical ward and diagnosed with incident delirium between 1 January 2012 and 31 December 2013. Controls were 321 patients sampled from the acute medical population admitted within the same time range, stratified for admission location and who did not develop incident delirium during hospitalisation.

RESULTS

Identified using logistic regression modelling, predisposing risk factors for incident delirium were dementia, cognitive impairment, functional impairment, previous delirium and fracture on admission. Precipitating risk factors for incident delirium were use of an indwelling catheter, adding more than three medications during admission and having an abnormal sodium level during admission.

CONCLUSIONS

Multiple risk factors for incident delirium exist; patients with a history of delirium, dementia and cognitive impairment are at greatest risk of developing delirium during hospitalisation.

RELEVANCE TO CLINICAL PRACTICE

Nurses and other healthcare professionals should be aware of patients who have one or more risk factors for incident delirium. Knowledge of risk factors for delirium has the potential to increase the recognition and understanding of patients who are vulnerable to delirium. Early recognition and prevention of delirium can contribute to improved patients safety and reduction in harm.

Risk factors for postoperative delirium after colorectal operation

BACKGROUND

A clear understanding of risk factors for postoperative delirium helps in the selection of individuals who might benefit from targeted perioperative intervention. The aim of this study was to identify risk factors for postoperative delirium after colorectal operation for malignancy.

METHODS

All consecutive patients who underwent elective or emergency operation because of malignancy of the colon, sigmoid, or rectum between 2009 and 2012 were included in this study. Potential risk factors for postoperative delirium were selected based on previous studies. These candidate factors were analyzed using univariate and multivariate logistic regression analysis. Based on this analysis, odds ratios and 95% confidence intervals were estimated.

RESULTS

A total of 436 patients underwent an oncologic resection of the colon, sigmoid, or rectum. Postoperative delirium was observed in 45 (10.3%) patients. Patients with a delirium had a greater in-hospital mortality rate (8.9% vs 3.6%, P = .09), spent more days in the intensive care unit, and had a longer total hospital stay. Variables associated with postoperative delirium in univariate analyses were age, American Society of Anesthesiologists classification, blood transfusion, history of psychiatric disease, history of cerebrovascular disease, postoperative pain management, postoperative renal impairment, C-reactive protein levels, leukocyte blood count, and postoperative complications. Independent risk factors were history of psychiatric disease (odds ratio 8.38, 95% confidence interval: 1.50-46.82), age (odds ratio 4.01, 95% confidence interval; 1.55-10.37), and perioperative blood transfusion (odds ratio 2.37, 95% confidence interval; 1.11-5.06).

CONCLUSION

This study shows that postoperative delirium is a frequently encountered complication after colorectal operation. Three independent risk factors for postoperative delirium were identified (history of psychiatric disease, age, and perioperative transfusion) that may contribute to risk estimation in this patient population.

Delirium in older adults: a chronic cognitive disorder?

Delirium is defined as a neurocognitive disorder characterized by sudden onset, fluctuating course, and disturbances in level of consciousness, attention, orientation, memory, thought, perception, and behavior (American Psychiatric Association, 2013). It occurs in hyperactive, hypoactive, or mixed forms in up to 50% of older hospital patients (Inouye et al., 2014) and 70% of older long-term care residents (McCusker et al., 2011), many with pre-existing dementia (Fick et al., 2002).

Sex Differences in Hip Fracture Surgery: Preoperative Risk Factors for Delirium and Postoperative Outcomes

OBJECTIVES

To describe the differences observed in risk factors for delirium and outcomes between men and women undergoing hip fracture repair surgery.

DESIGN

Prospective cohort study.

SETTING

Academic medical center.

PARTICIPANTS

Individuals with acute hip fracture admitted to an academic medical center (N = 431).

MEASUREMENTS

Information on preoperative demographic characteristics, medical history, laboratory results, and postoperative outcomes was obtained according to history and chart review. Delirium was assessed using the Confusion Assessment Method.

RESULTS

The overall incidence of postoperative delirium was 34%, with men more likely to experience postoperative delirium (44.8%) than women (30.2%) (P = .004). Male sex was associated with postoperative delirium in individuals with hip fracture, even after adjusting for other preoperative risk factors. Other significant preoperative risk factors included age, dementia, Parkinson's disease, and American Society of Anesthesiologists classification. Men were also more likely to experience other postoperative complications and have longer hospital length of stay.

CONCLUSION

Men are at higher risk of postoperative delirium after hip fracture repair than women and have more postoperative surgical complications. Their higher risk of postoperative delirium may be due to their underlying preoperative disease severity.

Cerebrospinal fluid levels of neopterin are elevated in delirium after hip fracture

BACKGROUND

The inflammatory cell product neopterin is elevated in serum before and during delirium. This suggests a role for disordered cell-mediated immunity or oxidative stress. Cerebrospinal fluid (CSF) neopterin levels reflect brain neopterin levels more closely than serum levels. Here we hypothesized that CSF neopterin levels would be higher in delirium.

METHODS

In this prospective cohort study, 139 elderly patients with acute hip fracture were recruited in Oslo and Edinburgh. Delirium was diagnosed with the confusion assessment method performed daily pre-operatively and on the first 5 days post-operatively. Paired CSF and blood samples were collected at the onset of spinal anaesthesia. Neopterin levels were measured using high-performance liquid chromatography.

RESULTS

Sixty-four (46 %) of 139 hip fracture patients developed delirium perioperatively. CSF neopterin levels were higher in delirium compared to controls (median 29.6 vs 24.7 nmol/mL, p = 0.003), with highest levels in patients who developed delirium post-operatively. Serum neopterin levels were also higher in delirium (median 37.0 vs 27.1 nmol/mL, p = 0.003). CSF neopterin remained significantly associated with delirium after controlling for relevant risk factors. Higher neopterin levels were associated with poorer outcomes (death or new institutionalization) 1 year after surgery (p = 0.02 for CSF and p = 0.03 for serum).

CONCLUSIONS

This study is the first to examine neopterin in CSF from patients with delirium. Our findings suggest potential roles for activation of cell-mediated immune responses or oxidative stress in the delirium process. High levels of serum or CSF neopterin in hip fracture patients may also be useful in predicting poor outcomes.

Frequency of full, partial and no recovery from subsyndromal deliriumin older hospital inpatients

OBJECTIVES

To determine the frequencies of full, partial and no recovery from subsyndromal delirium (SSD) in older hospital inpatients. A secondary objective was to compare the recovery status of patients with SSD or delirium.

METHODS

SSD was defined as acute onset of one or more Confusion Assessment Method core symptoms of delirium (fluctuation, inattention, disorganized thinking and altered level of consciousness) not meeting criteria for delirium and not progressing to delirium. The recovery status of medical or surgical inpatients aged 65 and older with SSD was assessed approximately 1 and 3 months after enrolment. Primary outcome categories were full recovery (no core symptoms of delirium), partial recovery (presence of one or more core symptoms but fewer symptoms than at enrolment), no recovery (same number of core symptoms as at enrolment) or death. Nominal logistic regression was used to compare the recovery status of patients with SSD or delirium.

RESULTS

Twenty-eight patients with SSD were enrolled. At the first follow-up, the frequencies of full, partial and no recovery and death were 40%, 12%, 32% and 16%, respectively; at the second follow-up, the frequencies were 54%, 8%, 21% and 17%, respectively. The frequency of full recovery was much higher in patients with SSD than delirium.

CONCLUSION

Small study sample size notwithstanding, the majority (54%) of patients with SSD recovered fully, but a substantial proportion (29%) had a protracted course. It may be important to monitor the longer-term course of SSD and develop strategies to ensure full recovery in all patients.

The short-term and long-term relationship between delirium and cognitive trajectory in older surgical patients

INTRODUCTION

As the relationship between delirium and long-term cognitive decline has not been well-explored, we evaluated this association in a prospective study.

METHODS

SAGES is an ongoing study involving 560 adults age 70 years or more without dementia scheduled for major surgery. Delirium was assessed daily in the postoperative period using the Confusion Assessment Method. General Cognitive Performance (GCP) and the Informant Questionnaire for Cognitive Decline in the Elderly were assessed preoperatively then repeatedly out to 36 months.

RESULTS

On average, patients with postoperative delirium had significantly lower preoperative cognitive performance, greater immediate (1 month) impairment, equivalent recovery at 2 months, and significantly greater long-term cognitive decline relative to the nondelirium group. Proxy reports corroborated the clinical significance of the long-term cognitive decline in delirious patients.

DISCUSSION

Cognitive decline after surgery is biphasic and accelerated among persons with delirium. The pace of long-term decline is similar to that seen with mild cognitive impairment.

Statins and delirium during critical illness: a multicenter, prospective cohort study

OBJECTIVE

Since statins have pleiotropic effects on inflammation and coagulation that may interrupt delirium pathogenesis, we tested the hypotheses that statin exposure is associated with reduced delirium during critical illness, whereas discontinuation of statin therapy is associated with increased delirium.

DESIGN

Multicenter, prospective cohort study.

SETTING

Medical and surgical ICUs in two large tertiary care hospitals in the United States.

PATIENTS

Patients with acute respiratory failure or shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We measured statin exposure prior to hospitalization and daily during the ICU stay, and we assessed patients for delirium twice daily using the Confusion Assessment Method for the ICU. Of 763 patients included, whose median (interquartile range) age was 61 years (51-70 yr) and Acute Physiology and Chronic Health Evaluation II was 25 (19-31), 257 (34%) were prehospital statin users and 197 (26%) were ICU statin users. Overall, delirium developed in 588 patients (77%). After adjusting for covariates, ICU statin use was associated with reduced delirium (p < 0.01). This association was modified by sepsis and study day; for example, statin use was associated with reduced delirium among patients with sepsis on study day 1 (odds ratio, 0.22; 95% CI, 0.10-0.49) but not among patients without sepsis on day 1 (odds ratio, 0.92; 95% CI, 0.46-1.84) or among those with sepsis later, for example, on day 13 (odds ratio, 0.70; 95% CI, 0.35-1.41). Prehospital statin use was not associated with delirium (odds ratio, 0.86; 95% CI, 0.44-1.66; p = 0.18), yet the longer a prehospital statin user's statin was held in the ICU, the higher the odds of delirium (overall p < 0.001 with the odds ratio depending on sepsis status and study day due to significant interactions).

CONCLUSIONS

In critically ill patients, ICU statin use was associated with reduced delirium, especially early during sepsis; discontinuation of a previously used statin was associated with increased delirium.

Predicting outcome in older hospital patients with delirium: a systematic literature review

OBJECTIVE

Delirium is a serious neuropsychiatric syndrome common in older hospitalised adults. It is associated with poor outcomes, however not all people with delirium have poor outcomes and the risk factors for adverse outcomes within this group are not well described. The objective was to report which predictors of outcome had been reported in the literature.

METHODS

We performed a systematic review by an initial electronic database search of MEDLINE, Embase and PsycINFO using four key search criteria. These were: (1) participants with a diagnosis of delirium, (2) clearly defined outcome measures, (3) a clearly defined variable as predictor of outcomes and (4) participants in the general hospital, rehabilitation and care home settings, excluding intensive care. Studies were then selected in a systematic fashion using specific predetermined criteria by three reviewers.

RESULTS

A total of 559 articles were screened, and 57 full text articles were assessed for eligibility. Twenty seven studies describing 18 different predictors of poor outcome were reported. The studies were rated by the Newcastle-Ottawa Score and were generally at low risk of bias. Four broad themes of predictor were identified; five delirium related predictors, two co-morbid psychiatric illness related predictors, eight patient related predictors and three biomarker related predictors. The most numerously described and clinically important appear to be the duration of the delirium episode, a hypoactive motor subtype, delirium severity and pre-existing psychiatric morbidity with dementia or depression. These are all associated with poorer delirium outcomes.

CONCLUSION

Important predictors of poor outcomes in patients with delirium have been demonstrated. These could be used in clinical practice to focus direct management and guide discussions regarding prognosis. These results also demonstrate a number of key unknowns, where further research to explore delirium prognosis is recommended and is vital to improve understanding and management of this condition.

Association of serum brain-derived neurotrophic factor (BDNF) and tumor necrosis factor-alpha (TNF-α) with diagnosis of delirium in oncology inpatients

OBJECTIVE

To evaluate brain-derived neurotrophic factor (BDNF) and tumor necrosis factor-α (TNF-α) blood levels as disease biomarkers of delirium in oncology inpatients.

METHODS

Seventeen oncology inpatients with delirium, 28 oncology inpatients without delirium, and 25 non-oncology controls (caregivers) were consecutively recruited from a Brazilian cancer center. This sample was matched by age, sex, and education level. The Confusion Assessment Method, the Mini-Mental State Examination, and the Digit Span Test were administered to ascertain delirium diagnosis. BDNF and TNF-α levels were measured by the Sandwich-ELISA method and flow cytometry, respectively. Blood samples were collected immediately after clinical evaluation.

RESULTS

Oncology inpatients (with and without delirium) showed significantly lower BDNF levels compared with non-oncology controls (F = 13.830; p = 0.001). TNF-α levels did not differ between the three groups.

CONCLUSION

A cross-sectional relationship of BDNF and TNF-α blood levels with delirium in oncology inpatients was not demonstrated. The association between cancer and reduced serum BDNF levels may be mediated by confounding factors.

Systemic Corticosteroids and Transition to Delirium in Critically Ill Patients

OBJECTIVE

Corticosteroids are frequently used in critically ill patients. We investigated whether systemic corticosteroid use increases the probability of transitioning to delirium in a large population of mixed medical-surgical ICU patients.

DESIGN

Prospective cohort study.

SETTING

A 32-bed medical-surgical ICU at an academic medical center.

PATIENTS

Critically ill adults (n = 1,112), admitted to the ICU for more than 24 hours without a condition that could hamper delirium assessment.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Systemic corticosteroid exposure was measured daily and converted to prednisone equivalents (milligrams). Daily mental status was classified as coma, delirium, or an awake without delirium state. Transitions between states were analyzed using a first-order Markov multinomial logistic regression model with 11 different covariables, with the transition from an awake without delirium state to delirium as a primary interest. Among the 1,112 patients, corticosteroids were administered on 35% (3,483/9,867) of the ICU days at a median dose of 50 mg (interquartile range, 25-75 mg) prednisone equivalent. Administration of a corticosteroid, and any increase in the dose of the corticosteroid given on exposure days, was not significantly associated with the transition to delirium (adjusted odds ratio, 1.08; 95% CI, 0.89-1.32 and adjusted odds ratio, 1.00; 95% CI, 0.99-1.01, per 10 mg increase in prednisone equivalent).

CONCLUSIONS

In a large population of mixed medical-surgical ICU patients, systemic corticosteroid use was not associated with an increased probability of transitioning to delirium.

High prolactin levels are associated with more delirium in septic patients

PURPOSES

We investigated whether high prolactin levels were associated with delirium in septic patients because neuropsychiatric disorders are frequently associated with hyperprolactinemia.

MATERIALS AND METHODS

Prolactin levels were measured daily for 4 days in 101 patients with sepsis. Delirium was assessed using the Richmond Agitation Sedation Scale and the Confusion Assessment Method in the ICU.

RESULTS

Delirium developed in 79 patients (78%) and was more common in patients older than 65 years. Prolactin levels were higher in patients with delirium than in those without over the 4 days of observation (P = .032). In patients with delirium, higher prolactin levels were associated with a lower incidence of nosocomial infection (P = .006). Multivariable logistic regression showed that the Sequential Organ Failure Assessment score at intensive care unit admission (odds ratio, 1.24; 95% confidence interval, 1.04-1.48; P = .002) and the combined effect of prolactin levels with age (odds ratio, 1.018; 95% confidence interval, 1.01-1.031; P = .006) were associated with the development of delirium.

CONCLUSIONS

High prolactin levels may be a risk factor for delirium in septic patients.

The importance of depression and alcohol use in coronary artery bypass graft surgery patients: risk factors for delirium and poorer quality of life

OBJECTIVE

To investigate whether depression, anxiety and stress increase the risk for delirium and poor quality of life (QOL) after coronary artery bypass (CABG) surgery.

METHODS

A total of 180 CABG patients (mean age of 63.5 ± 10.1 years, 82.2% males) completed baseline and postoperative self-report questionnaires to assess distress and QOL. Incident delirium was diagnosed postoperatively with a structured clinical interview and patients were monitored every day post-operatively for confusion and disturbance in consciousness.

RESULTS

Delirium developed in 63 persons (35% of sample). After adjustment for covariates, delirium was significantly associated with depression [odds ratio (OR): 1.08; 95% confidence interval (CI): 1.03-1.13, P = 0.003], anxiety (OR: 1.07; 95% CI: 1.02-1.13, P = 0.01) and stress (OR: 1.05; 95% CI: 1.00-1.09, P = 0.03). Preoperative depression scores were associated with poorer QOL including bodily pain (β = -0.39, P = 0.013), vitality (β = -0.32, P = 0.020), social functioning (β = -0.51, P ≤ 0.001), emotional role function (β = -0.44, P = 0.003) and general health (β = -0.33, P = 0.038). Among the covariates, harmful levels of alcohol use was consistently associated with poorer QOL.

CONCLUSIONS

Depression and harmful levels of alcohol use were consistently associated with poorer QOL whereas depression, anxiety and stress were associated with delirium risk. These findings point to further research examining depression and harmful levels of alcohol use in coronary heart disease populations undergoing coronary revascularization.

Partial and No Recovery from Delirium in Older Hospitalized Adults: Frequency and Baseline Risk Factors

OBJECTIVES

To determine the frequency and baseline risk factors for partial and no recovery from delirium in older hospitalized adults.

DESIGN

Cohort study with assessment of recovery status approximately 1 and 3 months after enrollment.

SETTING

University-affiliated, primary, acute-care hospital.

PARTICIPANTS

Medical or surgical inpatients aged 65 and older with delirium (N = 278).

MEASUREMENTS

The Mini-Mental State Examination (MMSE), Confusion Assessment Method (CAM), Delirium Index (DI), and activities of daily living (ADLs) were completed at enrollment and each follow-up. Primary outcome categories were full recovery (absence of CAM core symptoms of delirium), partial recovery (presence of ≥1 CAM core symptoms but not meeting criteria for delirium), no recovery (met CAM criteria for delirium), or death. Secondary outcomes were changes in MMSE, DI, and ADL scores between the baseline and last assessment. Potential risk factors included many clinical and laboratory variables.

RESULTS

In participants with dementia, frequencies of full, partial, and no recovery and death at first follow-up were 6.3%, 11.3%, 74.6%, and 7.7%, respectively; in participants without dementia, frequencies were 14.3%, 17%, 50.9%, and 17.9%, respectively. In participants with dementia, frequencies at the second follow-up were 7.9%, 15.1%, 57.6%, and 19.4%, respectively; in participants without dementia, frequencies were 19.2%, 20.2%, 31.7%, and 28.8%, respectively. Frequencies were similar in participants with prevalent and incident delirium and in medical and surgical participants. The DI, MMSE, and ADL scores of many participants with partial and no recovery improved. Independent baseline risk factors for delirium persistence were chart diagnosis of dementia (odds ratio (OR) = 2.51, 95% confidence interval (CI) =1.38, 4.56), presence of any malignancy (OR = 5.79, 95% CI = 1.51, 22.19), and greater severity of delirium (OR =9.39, 95% CI = 3.95, 22.35).

CONCLUSION

Delirium in many older hospitalized adults appears to be much more protracted than previously thought, especially in those with dementia, although delirium symptoms, cognition, and function improved in many participants with partial and no recovery. It may be important to monitor the longer-term course of delirium in older hospitalized adults and develop strategies to ensure full recovery.

Preoperative risk factors for postoperative delirium following hip fracture repair: a systematic review

OBJECTIVE

Systematically identify preoperative clinical risk factors for incident postoperative delirium in individuals undergoing hip fracture repair in order to guide clinicians in identifying high risk patients at admission.

METHODS

This is a systematic review of prospective observational studies with estimation of association between preoperative risk factors and incident postoperative delirium in multivariate models. Electronic searches were conducted in PubMed, Embase, PsycINFO, CINAHL, Cochrane Library, Proquest Dissertations and Theses, and WorldCatDissertations. Hand searches were conducted in selected journals and their supplements.

RESULTS

Search yielded 6380 titles and abstracts from electronic databases and 72 titles from hand searches, and 10 studies met inclusion criteria. The following risk factors were significant in bivariate models: cognitive impairment, age, gender, institutionalization, functional impairment, body mass index (BMI), albumin, comorbidities, American Society of Anesthesiologist classification, acute medical conditions, polypharmacy, and vision impairment. Among all of these risk factors, cognitive impairment most consistently remained statistically significant after adjusting for other risk factors in multivariate models, followed by BMI/albumin and multiple comorbidities.

CONCLUSION

In our systematic review, cognitive impairment was one of the strongest preoperative risk factors for postoperative delirium after hip fracture surgery. Preoperative cognitive assessment may be one of the most useful methods of identifying those who are at high risk for postoperative delirium and prioritizing delivery of delirium prevention measures.

Delirium symptoms during hospitalization predict long-term mortality in patients with severe pneumonia

INTRODUCTION

Delirium is common in critically ill patients and impact in-hospital mortality in patients with pneumonia. The aim of the study was to evaluate the prevalence of delirium symptoms during hospitalization in patients with severe pneumonia and their impact on one-year mortality.

METHODS

This was an observational, retrospective, cohort study of consecutive patients admitted to the respiratory high dependency unit of the San Gerardo University Hospital, Monza, Italy, between January 2009 and December 2012 with a diagnosis of severe pneumonia. A search through the charts looking for ten key words associated with delirium (confusion, disorientation, altered mental status, delirium, agitation, inappropriate behavior, mental status change, inattention, hallucination, lethargy) was performed by a multidisciplinary team. The primary endpoint was mortality at one-year follow-up. Secondary endpoint was in-hospital mortality.

RESULTS

A total of 172 patients were enrolled (78 % males; median age 75 years). At least one delirium symptom was detected in 53 patients (31 %) during hospitalization. The prevalence of delirium symptoms was higher among those who died during hospitalization vs. those who survived (44 vs. 27 %, p = 0.049, respectively). Seventy-one patients (46 %) died during the one-year follow-up. The prevalence of at least one delirium symptom was higher among those who died than those who survived during the one-year follow-up (39 vs. 21 %, p = 0.014, respectively). At the multivariable logistic regression analysis, after adjustment for age, comorbidities and severe sepsis, the presence of at least one delirium symptom during hospitalization was an independent predictor of one-year mortality (OR 2.35; 95 % CI 1.13-4.90; p = 0.023).

CONCLUSIONS

Delirium symptoms are independent predictors of one-year mortality in hospitalized patients with severe pneumonia. Further studies should confirm our results using prospective methods of collecting data.

Postoperative Delirium in the Geriatric Patient

Postoperative delirium, a common complication in older surgical patients, is independently associated with increased morbidity and mortality. Patients older than 65 years receive greater than one-third of the more than 40 million anesthetics delivered yearly in the United States. This number is expected to increase with the aging of the population. Thus, it is increasingly important that perioperative clinicians who care for geriatric patients have an understanding of the complex syndrome of postoperative delirium.

The interface between delirium and dementia in elderly adults

Delirium and dementia are two of the most common causes of cognitive impairment in older populations, yet their interrelation remains poorly understood. Previous studies have shown that dementia is the leading risk factor for delirium and that delirium is an independent risk factor for subsequent development of dementia. However, a major area of controversy is whether delirium is simply a marker of vulnerability to dementia, whether the effect of delirium is solely related to its precipitating factors, or whether delirium itself can cause permanent neuronal damage and lead to dementia. Ultimately, all of these hypotheses are likely to be true. Emerging evidence from epidemiological, clinicopathological, neuroimaging, biomarker, and experimental studies lends support to a strong relation between delirium and dementia, and to both shared and distinct pathological mechanisms. New preventive and therapeutic approaches that target delirium might offer a sought-after opportunity for early intervention, preservation of cognitive reserve, and prevention of irreversible cognitive decline in ageing.

Review of delirium in patients with Parkinson's disease

Parkinson's disease (PD) is common and has a number of associated neuropsychiatric disturbances. Of these, delirium has historically been under-recognised. Delirium is an acute disturbance of attention and awareness that fluctuates, and is accompanied by an additional disturbance of cognition. As delirium is known to carry a particularly poor prognosis in terms of morbidity and mortality, and the relationship between delirium and dementia is becoming better defined, we completed a literature review of delirium in the context of PD. A literature search was completed using the databases PubMed, Embase and Ovid Medline. PubMed (1945-2014) was searched in September 2014; Embase (1974-2014); and Ovid Medline (1946-2014) in October 2014. The search terms 'delirium' and 'Parkinsons' in combination were used. Large studies using a robust definition of delirium were lacking in PD. There is the suggestion that PD is a risk factor for delirium and that delirium negatively impacts upon the motor symptom trajectory. Deficits in the neurotransmitters dopamine and acetylcholine are implicated in the pathophysiology of delirium in PD. Systemic inflammation also appears to have a role. Treatment of delirium in PD should include medication review and cautious use of atypical antipsychotics where pharmacological treatment is indicated. Of the atypical antipsychotics studied, quetiapine has the least extrapyramidal side effects. Evidence suggests a specific link between delirium and PD but well-designed clinical studies to evaluate the prevalence, impact and treatment of delirium in PD are required. Given the potential to improve outcomes through delirium prevention we conclude that delirium in PD is an area worthy of further study.

Is there a role for monocyte chemoattractant protein-1 in delirium? Novel observations in elderly hip fracture patients

Background

Delirium is common, associated with poor outcome, but its pathophysiology remains obscure. The aim of the present study was to study a possible role of monocyte chemoattractant protein-1 (MCP-1) in the development of delirium.

Findings

A prospective cohort of 19 hip fracture patients (median age 83 years) were screened for delirium daily by validated methods. MCP-1 was measured on arrival and postoperatively. The number of patients with a raise in MCP-1 was statistically significantly higher in the group with delirium in the postoperative phase compared to the no-delirium group (5/6 vs. 1/7, p = .03).

Conclusions

MCP-1 might play a role in the development of delirium.

The protocol of the Oslo Study of Clonidine in Elderly Patients with Delirium; LUCID: a randomised placebo-controlled trial

Background

Delirium affects 15% of hospitalised patients and is linked with poor outcomes, yet few pharmacological treatment options exist. One hypothesis is that delirium may in part result from exaggerated and/or prolonged stress responses. Dexmedetomidine, a parenterally-administered alpha2-adrenergic receptor agonist which attenuates sympathetic nervous system activity, shows promise as treatment in ICU delirium. Clonidine exhibits similar pharmacodynamic properties and can be administered orally. We therefore wish to explore possible effects of clonidine upon the duration and severity of delirium in general medical inpatients.

Methods/Design

The Oslo Study of Clonidine in Elderly Patients with Delirium (LUCID) is a randomised, placebo-controlled, double-blinded, parallel group study with 4-month prospective follow-up. We will recruit 100 older medical inpatients with delirium or subsyndromal delirium in the acute geriatric ward. Participants will be randomised to oral clonidine or placebo until delirium free for 2 days (Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria), or after a maximum of 7 days treatment. Assessment of haemodynamics (blood pressure, heart rate and electrocardiogram) and delirium will be performed daily until discharge or a maximum of 7 days after end of treatment. The primary endpoint is the trajectory of delirium over time (measured by Memorial Delirium Assessment Scale). Secondary endpoints include the duration of delirium, use of rescue medication for delirium, pharmacokinetics and pharmacodynamics of clonidine, cognitive function after 4 months, length of hospital stay and need for institutionalisation.

Discussion

LUCID will explore the efficacy and safety of clonidine for delirium in older medical inpatients.

Trial registration

ClinicalTrials.gov NCT01956604. EudraCT Number: 2013-000815-26

Postoperative delirium and pre-fracture disability predict 6-month mortality among the oldest old hip fracture patients

BACKGROUND

Age is one of the most robust risk factors for hip fracture. Recent projections indicate that almost half of hip fractures are occurring with an increasing trend among the "oldest old" (i.e., in those aged >85 years).

AIMS

To compare clinical characteristics, outcomes, and risk factors for 6-month mortality in two groups of "oldest old" patients (group 1 = 85-89, group 2 > 90 years), after hip fracture surgery.

METHODS

Observational prospective cohort study with 6-month follow-up, performed in an Orthogeriatric Unit of an academic hospital between March 2007 and November 2012.

RESULTS

Two hundred seventy-five patients (group 1: N = 171; group 2: N = 104) underwent a comprehensive geriatric assessment, including demographics, clinical, functional, nutritional, and mental status. The 6-month rehospitalization and mortality rates after surgery were assessed through structured telephone interviews with patient's caregivers. Multivariate logistic regression models were used to evaluate predictors of 6-month mortality, adjusting for relevant covariates. Fifty-eight patients died at follow-up. The in-hospital and 6-month mortality rates were significantly higher for patients of group 2 than for those of group 1. After adjusting for covariates, the multivariate logistic regressions showed that severe disability (OR 2.24, 95 % CI 1.08-4.65) and postoperative delirium (POD) (OR 3.80, 95 % CI 1.72-8.39) were predictors of 6-month mortality.

CONCLUSIONS

Patients aged >90 years who underwent hip fracture surgery are more likely to die at 6 months than those aged 85-89 years. Pre-fracture disability and POD are predictors of this excess of mortality.

Diagnostic and treatment practices of delirium in a general hospital

BACKGROUND

Despite the increase in research on delirium, it remains underdiagnosed and difficult to manage, and the outcome is poor especially in older people.

AIMS

To identify the clinically diagnosed rates of delirium, the possible aetiologies, to describe treatment, number and type of psychotropic medication used and to investigate the reasons for referral to a liaison psychiatric team.

METHODS

Retrospective study of medical records of inpatients admitted to Sligo Regional Hospital during an 18-month period.

RESULTS

One hundred and fifty-six files had a documentation of delirium (time prevalence 2%). Mean age of the sample was 82 years (SD = 7.2), 66 (42%) were male. Sixty-nine (44.2%) of the total sample had a previous history of dementia, and 57 (36.5%) had a previous history of delirium. In 67 (43.2%) samples, the cause was infection, while in 4, no specific cause was identified. Ninety (58%) were referred to the liaison service, but only in 26 (28.9 %), the reason for referral was "acute confusion" or "delirium". In a majority of referrals, the reason was an affective disorder more often depression. There were no significant differences between delirium subtypes and referrals (χ(2) = 3.868, df 3, p = 0.28). Examination of the amount of antipsychotics prescribed before, during and after delirium shows that there was a significant increase in use during the delirium (χ(2) = 17.512, df 8, p = 0.025) and decrease in z-hypnotics medication (zopiclone/zolpidem), (χ(2) = 20.114, df 4, p < 0.001), while benzodiazepines and antidepressants remained the same.

CONCLUSIONS

Delirium is often misdiagnosed and unrecognized in hospital settings; however, when identified the pharmacological management is appropriate.

The attributable mortality of delirium in critically ill patients: prospective cohort study

OBJECTIVE

To determine the attributable mortality caused by delirium in critically ill patients.

DESIGN

Prospective cohort study.

SETTING

32 mixed bed intensive care unit in the Netherlands, January 2011 to July 2013.

PARTICIPANTS

1112 consecutive adults admitted to an intensive care unit for a minimum of 24 hours.

EXPOSURES

Trained observers evaluated delirium daily using a validated protocol. Logistic regression and competing risks survival analyses were used to adjust for baseline variables and a marginal structural model analysis to adjust for confounding by evolution of disease severity before the onset of delirium.

MAIN OUTCOME MEASURE

Mortality during admission to an intensive care unit.

RESULTS

Among 1112 evaluated patients, 558 (50.2%) developed at least one episode of delirium, with a median duration of 3 days (interquartile range 2-7 days). Crude mortality was 94/558 (17%) in patients with delirium compared with 40/554 (7%) in patients without delirium (P<0.001). Delirium was significantly associated with mortality in the multivariable logistic regression analysis (odds ratio 1.77, 95% confidence interval 1.15 to 2.72) and survival analysis (subdistribution hazard ratio 2.08, 95% confidence interval 1.40 to 3.09). However, the association disappeared after adjustment for time varying confounders in the marginal structural model (subdistribution hazard ratio 1.19, 95% confidence interval 0.75 to 1.89). Using this approach, only 7.2% (95% confidence interval -7.5% to 19.5%) of deaths in the intensive care unit were attributable to delirium, with an absolute mortality excess in patients with delirium of 0.9% (95% confidence interval -0.9% to 2.3%) by day 30. In post hoc analyses, however, delirium that persisted for two days or more remained associated with a 2.0% (95% confidence interval 1.2% to 2.8%) absolute mortality increase. Furthermore, competing risk analysis showed that delirium of any duration was associated with a significantly reduced rate of discharge from the intensive care unit (cause specific hazard ratio 0.65, 95% confidence interval 0.55 to 0.76).

CONCLUSIONS

Overall, delirium prolongs admission in the intensive care unit but does not cause death in critically ill patients. Future studies should focus on episodes of persistent delirium and its long term sequelae rather than on acute mortality.Trial registration Clinicaltrials.gov NCT01905033.

EFFECT OF PREOPERATIVE PAIN AND DEPRESSIVE SYMPTOMS ON THE DEVELOPMENT OF POSTOPERATIVE DELIRIUM

BACKGROUND

Preoperative pain and depression predispose patients to delirium. Our goal was to determine whether pain and depressive symptoms interact to increase delirium risk.

METHODS

We enrolled 459 persons without dementia aged ≥70 years scheduled for elective orthopedic surgery. At baseline, participants reported their worst and average pain within seven days and current pain on a 0-10 scale. Depressive symptoms were assessed using the 15-item Geriatric Depression Scale and chart. Delirium was assessed with the Confusion Assessment Method and chart. We examined the relationship between preoperative pain, depressive symptoms and delirium using multivariable analysis of pain and delirium stratified by presence of depressive symptoms.

FINDINGS

Delirium, occurring in 23% of the sample, was significantly higher in those with depressive symptoms at baseline than those without (relative risk, RR, 1·6, 95% confidence interval, CI, 1·2-2·3). Preoperative pain was associated with an increased adjusted risk for delirium across all pain measures (RR from 1·07-1·08 per point of pain). In stratified analyses, patients with depressive symptoms had a 21% increased risk for delirium for each one-point increase in worst pain score, demonstrating a significant interaction (P=0·049). Similarly, a significant 13% increased risk for delirium was demonstrated for a one-point increase in average pain score, but the interaction did not achieve statistical significance.

INTERPRETATION

Preoperative pain and depressive symptoms demonstrated increased risk for delirium independently and with substantial interaction, suggesting a cumulative impact. Thus, pain and depression are vulnerability factors for delirium that should be assessed before surgery.

FUNDING

U.S. National Institute on Aging.

Effect of melatonin on incidence of delirium among patients with hip fracture: a multicentre, double-blind randomized controlled trial

BACKGROUND

Disturbance of the sleep-wake cycle is a characteristic of delirium. In addition, changes in melatonin rhythm influence the circadian rhythm and are associated with delirium. We compared the effect of melatonin and placebo on the incidence and duration of delirium.

METHODS

We performed this multicentre, double-blind, randomized controlled trial between November 2008 and May 2012 in 1 academic and 2 nonacademic hospitals. Patients aged 65 years or older who were scheduled for acute hip surgery were eligible for inclusion. Patients received melatonin 3 mg or placebo in the evening for 5 consecutive days, starting within 24 hours after admission. The primary outcome was incidence of delirium within 8 days of admission. We also monitored the duration of delirium.

RESULTS

A total of 452 patients were randomly assigned to the 2 study groups. We subsequently excluded 74 patients for whom the primary end point could not be measured or who had delirium before the second day of the study. After these postrandomization exclusions, data for 378 patients were included in the main analysis. The overall mean age was 84 years, 238 (63.0%) of the patients lived at home before admission, and 210 (55.6%) had cognitive impairment. We observed no effect of melatonin on the incidence of delirium: 55/186 (29.6%) in the melatonin group v. 49/192 (25.5%) in the placebo group; difference 4.1 (95% confidence interval -0.05 to 13.1) percentage points. There were no between-group differences in mortality or in cognitive or functional outcomes at 3-month follow-up.

INTERPRETATION

In this older population with hip fracture, treatment with melatonin did not reduce the incidence of delirium.

TRIAL REGISTRATION

Netherlands Trial Registry, NTR1576: MAPLE (Melatonin Against PLacebo in Elderly patients) study; www.trialregister.nl/trialreg/admin/rctview.asp?TC=1576.

Delirium and depression: inter-relationship and clinical overlap in elderly people

Delirium and depression are complex neuropsychiatric syndromes common in the elderly and are associated with poor health-care outcomes. Accurate diagnosis is essential to the provision of optimum health care for individuals with these conditions but is complicated by substantial clinical overlap in symptoms and comorbidities. A careful assessment of the patient's symptoms, including their context and time course, is needed for accurate diagnosis. Previous depression is common in patients with delirium and depressive illness is a recognised sequelae of delirium. The two syndromes seem to be caused by similar pathophysiological mechanisms, involving disturbances in stress and inflammatory responses, monoaminergic and melatonergic signalling, which point to new avenues for therapeutic intervention. Improved methods to assess delirium and depression in populations at high risk by virtue of their age, diminished cognitive reserve and physical frailty is a key target to achieve improved health-care outcomes in elderly individuals.

Cerebrospinal fluid markers of neuroinflammation in delirium: a role for interleukin-1β in delirium after hip fracture

OBJECTIVE

Exaggerated central nervous system (CNS) inflammatory responses to peripheral stressors may be implicated in delirium. This study hypothesised that the IL-1β family is involved in delirium, predicting increased levels of interleukin-1β (IL-1β) and decreased IL-1 receptor antagonist (IL-1ra) in the cerebrospinal fluid (CSF) of elderly patients with acute hip fracture. We also hypothesised that Glial Fibrillary Acidic Protein (GFAP) and interferon-γ (IFN-γ) would be increased, and insulin-like growth factor 1 (IGF-1) would be decreased.

METHODS

Participants with acute hip fracture aged >60 (N=43) were assessed for delirium before and 3-4 days after surgery. CSF samples were taken at induction of spinal anaesthesia. Enzyme-linked immunosorbent assays (ELISA) were used for protein concentrations.

RESULTS

Prevalent delirium was diagnosed in eight patients and incident delirium in 17 patients. CSF IL-1β was higher in patients with incident delirium compared to never delirium (incident delirium 1.74 pg/ml (1.02-1.74) vs. prevalent 0.84 pg/ml (0.49-1.57) vs. never 0.66 pg/ml (0-1.02), Kruskal-Wallis p=0.03). CSF:serum IL-1β ratios were higher in delirious than non-delirious patients. CSF IL-1ra was higher in prevalent delirium compared to incident delirium (prevalent delirium 70.75 pg/ml (65.63-73.01) vs. incident 31.06 pg/ml (28.12-35.15) vs. never 33.98 pg/ml (28.71-43.28), Kruskal-Wallis p=0.04). GFAP was not increased in delirium. IFN-γ and IGF-1 were below the detection limit in CSF.

CONCLUSION

This study provides novel evidence of CNS inflammation involving the IL-1β family in delirium and suggests a rise in CSF IL-1β early in delirium pathogenesis. Future larger CSF studies should examine the role of CNS inflammation in delirium and its sequelae.

Current readings: neurocognitive impairment and clinical implications after cardiac surgery

The earliest reports of cardiac surgery literatures reported evidence of neurocognitive decline, highlighted in the 1995 statement of Consensus on assessment of neurobehavioral outcomes after cardiac surgery. Until now, the magnitude and clinical importance of neurocognitive outcomes continues to fluctuate and lack clarity. The aim of this review is to evaluate the contemporary status of neurocognitive outcomes in relation to pre-existing impairment, revascularization strategy, broader cardiovascular pathophysiological processes, and any longer-term clinical implications. Five studies published between 2009 and 2013 were reviewed. A meta-analysis did not find differences between on- and off-pump procedures. In other studies, there was evidence for extensive preoperative neurocognitive impairments. Additional 2 studies showed that longer-term neurocognitive impairment, including dementia, was not dissimilar to nonsurgical patients with cardiovascular disease. Currently, there is no convincing evidence to suggest that cardiac surgery, and cardiopulmonary bypass in particular, has a causal role in progression to dementia, or long-term deficit, independent of pre-existing neurocognitive impairments and cardiovascular disease.

The pharmacologic management of delirium in children and adolescents

Delirium is a serious and common problem in severely medically ill patients of all ages. It has been less addressed in children and adolescents. Treatment of delirium is predicated on addressing its underlying cause. The management of its symptoms depends on the off-label use of antipsychotics, while avoiding agents that precipitate or worsen delirium. Olanzapine, quetiapine, and risperidone are presently considered first-line drugs, usually replacing haloperidol. Other agents have shown promise, including melatonin to address the sleep disturbance characteristic of delirium, and dexmedetomidine, an α2-agonist, that may facilitate lower doses of benzodiazepines and opioids that may worsen delirium.

Preoperative plasma leptin levels predict delirium in elderly patients after hip fracture surgery

Leptin is considered to be a modulator of the immune response. Hypoleptinemia increases the risk for Alzheimer's disease and vascular dementia. The present study aimed to investigate the ability of plasma leptin level to predict delirium in elderly patients after hip fracture surgery. Postoperative delirium (pod) was evaluated using the Confusion Assessment Method. Prolonged postoperative delirium (ppod) was defined as delirium lasting more than 4 weeks. Plasma leptin levels of 186 elderly patients and 186 elderly controls were measured by an enzyme-linked immunosorbent assay. Plasma leptin level was substantially lower in patients than in controls (4.6±2.2ng/ml vs. 7.5±1.8ng/ml, P<0.001). It was identified as an independent predictor for pod [odds ratio, 0.385; 95% confidence interval (CI), 0.286-0.517; P<0.001] and ppod (odds ratio, 0.283; 95% CI, 0.152-0.527; P<0.001) using a multivariate analysis, and had high area under receiver operating characteristic curve for pod [area under curve (AUC), 0.850; 95% CI, 0.790-0.898] and ppod (AUC, 0.890; 95% CI, 0.836-0.931). The predictive value of leptin was markedly bigger than that of age for pod (AUC, 0.705; 95% CI, 0.634-0.770; P=0.002) and ppod (AUC, 0.713; 95% CI, 0.642-0.777; P=0.019). In a combined logistic-regression model, leptin improved the AUC of age to 0.890 (95% CI, 0.836-0.931) (P<0.001) for pod and 0.910 (95% CI, 0.860-0.947) (P=0.005) for ppod. Thus, preoperative plasma leptin level may be a useful, complementary tool to predict delirium and also prolonged delirium in elderly patients after hip fracture surgery.

Delirium and high fever are associated with subacute motor deterioration in Parkinson disease: a nested case-control study

Background

In Parkinson disease (PD), systemic inflammation caused by respiratory infections such as pneumonia frequently occurs, often resulting in delirium in the advanced stages of this disease. Delirium can lead to cognitive and functional decline, institutionalization, and mortality, especially in the elderly. Inflammation causes rapid worsening of PD motor symptoms and signs, sometimes irreversibly in some, but not all, patients.

Purpose

To identify factors associated with subacute motor deterioration in PD patients with systemic inflammation.

Methods

The association of clinical factors with subacute motor deterioration was analyzed by a case-control study. Subacute motor deterioration was defined as sustained worsening by one or more modified Hoehn and Yahr (H–Y) stages. Using multivariable logistic regression incorporating baseline characteristics (age, sex, PD duration, modified H–Y stage, dementia, and psychosis history) and statistically selected possible predictors (peak body temperature, duration of leukocytosis, and presence of delirium), the odds ratios for these factors were estimated as relative risks.

Results

Of 80 PD patients with systemic inflammation, 26 with associated subacute motor deterioration were designated as cases and the remainder as controls. In the 26 cases, 6 months after its onset the motor deterioration had persisted in 19 patients and resolved in four (three were lost for follow-up). Multivariable logistic regression analysis showed that delirium and body temperature are significantly associated with motor deterioration after systemic inflammation (P = 0.001 for delirium and P = 0.026 for body temperature), the adjusted odds ratios being 15.89 (95% confidence interval [CI]: 3.23–78.14) and 2.78 (95% CI: 1.13–6.83), respectively.

Conclusions

In patients with PD and systemic inflammation, delirium and high body temperature are strong risk factors for subsequent subacute motor deterioration and such deterioration can persist for over 6 months.

Postoperative delirium in a substudy of cardiothoracic surgical patients in the BAG-RECALL clinical trial

BACKGROUND

Postoperative delirium in the intensive care unit (ICU) is a frequent complication after cardiac or thoracic surgery and is associated with increased morbidity and mortality.

METHODS

In this single-center substudy of the BAG-RECALL trial (NCT00682825), we screened patients after cardiac or thoracic surgery in the ICU twice daily for delirium using the Confusion Assessment Method for the ICU. The primary outcome was the incidence of delirium in patients who had been randomized to intraoperative Bispectral Index (BIS)-guided and end-tidal anesthetic concentration-guided depth of anesthesia protocols. As a secondary analysis, a Bayesian stochastic search variable selection strategy was used to rank a field of candidate risk factors for delirium, followed by binary logistic regression.

RESULTS

Of 310 patients assessed, 28 of 149 (18.8%) in the BIS group and 45 of 161 (28.0%) in the end-tidal anesthetic concentration group developed postoperative delirium in the ICU (odds ratio 0.60, 95% confidence interval, 0.35-1.02, P= 0.058). Low average volatile anesthetic dose, intraoperative transfusion, ASA physical status, and European System for Cardiac Operative Risk Evaluation were identified as independent predictors of delirium.

CONCLUSIONS

A larger randomized study should determine whether brain monitoring with BIS or an alternative method decreases delirium after cardiac or thoracic surgery. The association between low anesthetic concentration and delirium is a surprising finding and could reflect that patients with poor health are both more sensitive to the effects of volatile anesthetic drugs and are also more likely to develop postoperative delirium. Investigation of candidate methods to prevent delirium should be prioritized in view of the established association between postoperative delirium and adverse patient outcomes.

Hospitalization and cognitive decline: Can the nature of the relationship be deciphered?

BACKGROUND

Evidence for a relationship between hospitalization and incident cognitive decline exists mainly in the literature focusing on critical care hospitalization. Recent studies, however, have also found an association between noncritical care hospitalization and the development of cognitive decline.

OBJECTIVE

This article will review the literature pertaining to hospitalization and cognitive decline, including hospitalizations for both critical and noncritical care, and in medical and surgical patients. The article will also explore the various factors that have been implicated in the development of cognitive decline and dementia.

METHODS

Review of the literature was completed using PubMed and Medline search programs.

RESULTS

Several articles supporting evidence for the association between hospitalization and cognitive decline are available. Evidence for potential mediating factors also does exist.

CONCLUSIONS

There is evidence to support an association between hospitalization and development of cognitive decline. Factors that could mediate this association include, but may not be limited to, delirium, medications, stress, and depression. There is a need for further research in this area in order to better understand the underlying pathophysiology involved in the development of cognitive decline and dementia and to determine if preventive measures might be beneficial in decreasing risk for cognitive decline for patients who are hospitalized.