Incidence
The incidence in the UK in ventilated critically ill patients is 55% to 69%. This audit data has been collected from a number of centres and presented as poster presentations at Intensive Care conferences. Refs.
The incidence is less in less sick patients. So, for example the incidence at Watford General Hospital, a typical UK district and general HDU/ITU using a validated screening tool, the CAM-ICU, the overall incidence is 28%, if you exclude elective post-operative patients it is 38% and in ventilated patients only it is 63%.
Internationally the incidence varies from 20% to 50% in lower-severity patients to 60% up to 80% in ventilated patients with APACHE scores greater than 25. Refs.
Patients get delirium or not depending on how vulnerable they are. How many predisposing factors do they have? On top of which are added one or more precipitating factors that trigger the delirium.
For instance a patient who has pre-existing cognitive impairment is likely to become delirious with a urinary tract infection. A patient with more than 3 risk factors has a 60% chance of developing delirium – critically ill patients can have up to 10.
The single most important modifiable risk factor in critical care is the use of sedative drugs. See management.
Death
Delirium is an independent predictor of death in intensive care patients. This means after adjusting for pre-existing co morbidity and cognitive impairment, ICU diagnosis AND severity of illness delirious patients are 2 to 3 times more likely to die. Each additional day spent in delirium is associated with a 20% increase risk of prolonged hospitalization and a 10% increased risk of death.
ICU delirium is predictive of a 3-fold higher reintubation rate and over 10 additional days in the hospital and all the financial and human costs this incurs.
Dementia
Investigations into the relationship between delirium and long-term cognitive outcomes have consistently demonstrated a link. Emerging data indicates delirium may lead to or accelerate dementia. One third of ventilated ICU patients have long-term cognitive impairment persisting at 3 years. MMSE scores of delirious patients are 5 points lower than patients without delirium one year later after adjusting for co-morbidity and severity of illness. In practice? Your patient after leaving ITU is unable to return to anything like the life they enjoyed before.
UK
- Delirium in the Critically Ill: An evaluation of the Incidence, Preventative Techniques and Treatments on the Critical Care Unit. H Lees & D Conway (Manchester)
Poster at ICS State of Art December 2007
18.8% level 2, 69% ventilated patients - Confused – You will be! How common is delirium in critically ill patients? Frame et al (Edinburgh) Poster at ICS State of Art December 2007.
55% - 10 out of 18 ventilated patients. Nice example of a small set of patients from the UK showing pilot data about the high incidence of this form of organ dysfunction. EW - Routine delirium monitoring in a UK critical care is feasible and identifies a high incidence of unrecognised delirium. V Page and S Navarange. (Watford)
Poster ESICM Sept 2008 38% acute admissions (vent +non-vent), 62% incidence in assessable ventilated patients - The incidence of delirium in intensive care patients and association with GABA agonist administration. J Snell et al. (Liverpool)
Poster ESICM Sept 2008
One of the major drug classes given is known to be deliriogenic. 24% vent+non-vent - Retrospective audit data personal communication V Page, Watford.
60 ventilated patients, incidence 64% of the 48 assessable patients.
Outside UK
- Informed consent in the critically ill: A two-step approach incorporating delirium screening. Fan E et al.
Link
CCM 2008; 36: 94-99
Very interesting concept related to need for delirium evaluations prior to consenting. Issue is controversial and not fully fleshed out at this stage. EW - Comparison of confusion assessment method for the intensive care unit (CAM-ICU) with the Intensive Care Delirium Screening Checklist (ICDSC) for delirium in critical care patients gives high agreement rate(s). Plaschke et al.
ICM 2008; 34: 431-36.
Link
Much room in the future for comparisons like this. For now, suffice it to say that there are several validated delirium instruments for use, and that variations in rates are expected because of slightly different criteria utilized. The CAM-ICU is the most reproducibly validated and only instrument with precedent for use in large RCTs published already in high impact journals. EW - Confusion assessment method for the intensive care unit (CAM-ICU): translation, retranslation and validation into Swedish intensive care settings. Larsson et al.
Link
Acta Anes Scand 2007; 51: 888-92
There are now over a dozen different language translations of the CAM-ICU, which makes this the most widely applicable tool on a global scale by which to evaluate critically ill patients at the bedside for delirium in the ICU. EW - Subsyndromal delirium in the ICU: evidence for a disease spectrum. Ouimet et al. ICM 2007; 33: 1007-13
Link
There is no doubt that many patients have some elements of delirium but not the full syndrome. This article is an early look into this concept and provides important thoughts about considering different levels of organ failure. Ongoing work with delirium scoring will facilitate this area of work. EW - Incidence, risk factors and consequences of ICU delirium. Ouimet et al.
ICM 2007; 33: 66-73
Link
31.8% ICDCS. VJP - Intensive care delirium is an independent predictor of longer hospital stay: a prospective analysis of 261 non-ventilated patients. Thomason et al Critical Care 2005; 9: 375-81
Link
This study showed that even non-intubated patients in the ICU have up to a 50% prevalence of brain organ dysfunction (delirium), and that its presence was a predictor of longer hospital stay. EW - Delirium as detected by the CAM-ICU predicts restraint use among mechanically ventilated patients. Micek et al.
Link
CCM 2005; 33: 1260-65
Physical restraints may be a cause of delirium and a result of delirium. This begins to look into this relationship. EW - The impact of delirium on the survival of mechanically ventilated patients. Lin et al. CCM 2004; 32: 2254-59 (note editorial Wes Ely)
Link
A study showing again the independent relationship between delirium and mortality and also re-validating the CAM-ICU against the accepted reference standard – the DSM IV criteria. EW Low incidence (11%) partially explained by study case mix. VJP - Delirium as a predictor of mortality in mechanically ventilated patients in the intensive care unit. Ely et al.
Link
JAMA 2004; 291: 1753-62
This NIH-sponsored study showed that delirium in ICU patients (defined using the CAM-ICU) was an independent predictor a 3-fold higher likelihood of death by 6 months, as well as a 10-fold higher likelihood of cognitive impairment at hospital discharge even after adjusting for relevant covariates. EW - Delirium in Intensive Care Unit: occurrence and clinical course in older patients.
Link
McNicoll et al. JAGS 2003; 51: 591-598.
Delirium in the older ICU patients (defined using the CAM-ICU) was an independent predictor of higher re-hospitalization rates. EW - Delirium in mechanically ventilated patients. Validity and reliability of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU). Ely et al.
Link
JAMA; 2001: 286: 2703-2710.
This study provided the largest validation study to date of any delirium monitoring instrument and the first based on the DSM IV criteria widely accepted as the reference standard. In this study, the CAM-ICU was found to have a 95% accuracy against a neuropsychiatric expert using the DSM, and the reliability data showed a kappa of >0.90 across physicians and nurses. EW - The impact of delirium in the intensive care unit on hospital length of stay. Ely et al. ICM 2001; 27: 1892-1900
Link
First study showing ICU delirium independently related to hospital length of stay. EW - Intensive Care Delirium Screening Checklist: evaluation of a new screening tool. Bergeron et al.
Link
ICM 2001; 27: 859-64
This was the first study published of any delirium instrument validated in ICU patients, some of whom were on the ventilator. The ICDSC is a good checklist by which to follow a patient throughout the course of a day to detect the development of delirium. EW
Risks
- Characteristics associated with delirium in older patients in a medical intensive care unit. Pisani et al.
Link
Arch Intern Med 2007; 167: 1629-34
Inouye gp. Incidence 70.4%, dementia OR 6.3, benzos pre-admission OR 3.4, elevated CR OR 2.1, decr pH OR 2.1. VJP - Risk factors for delirium at discharge Inouye et al.
Link
Arch Intern Med 2007;167:1406-13 - Incidence, risk factors and consequences of ICU delirium. Ouimet et al.
ICM 2007; 33: 66-73 (rpt from incidence ref list)
Hypertension, alcoholism, higher APACHE scores & sed. Induced coma. VJP - Delirium and its motoric subtypes: a study of 614 critically ill patients. Peterson et al.
Link
JAGS 2006; 54: 479-84
Large study showing that hyperactive delirium is the minority issue related to this organ dysfunction. Hypoactive and mixed forms of delirium are much more common, and an older population brings even more of the hypoactive component of delirium, making it particularly important to routinely monitor for this and to incorporate this into clinical trial design. EW - Risk factors and prediction of postoperative delirium in elderly hip-surgery patients: implementation and validation of a medical risk factor model. Kalisvaart et al.
Link
JAGS 2006; 54: 817-22
Incidence 31.8%, high risk – age, illness severity & cog impairment significant VJP - Impaired oxidative metabolism precipitates delirium: A study of 101 ICU patients. Seaman et al.
Link
Psychosomatics 2006; 47: 56-61 - Lorazepam is an independent risk factor for transitioning to delirium in intensive care patients. Pandharipande et al.
Link
Anesthesiology 2006; 104: 21-6
First study to document with time-dependent covariate analysis the fact that the benzodiazepine was the most significant medication associated with transition to delirium in mechanically ventilated patients. EW - Postoperative delirium in elderly patients after major abdominal surgery. Olin et al.
Link
British Journal of Surgery 2005; 92: 1559-64.
26/ 51 patients, significant difference in need for blood transfusions VJP - Psychoactive medications and risk of delirium in hospitalized cancer patients. Gaudreau et al.
Link
J of Clin Oncol. 2005; 23: 6712-18 - Risk factors for post-operative delirium after liver resection for hepatocellular carcinoma. Yoshimura et al.
Link
World J. Surg. 2004; 28: 982-86 - Severe agitation among ventilated medical intensive care patients: frequency, characteristics and outcomes. Woods et al.
Link
ICM 2004; 30: 1066-72 - Delirium in an intensive care unit: a study of risk factors. Dubois et al
Link
ICM 2001; 27: 1297-1304
Hypertension, smoking, abnormal bilirubin, epidural and morphine use VJP
Interventions & outcomes
- Efficacy and safety of a paired sedation and ventilator weaning protocol for mechanically ventilated patients in intensive care (Awakening and Breathing Controlled trial): a randomised controlled trial. Girard et al
Link
Lancet 371 (9607):126-134, 2008.
Multicenter trial documenting that a protocol reducing exposure to sedatives and analgesics via daily spontaneous awakening trials coupled with daily spontaneous breathing trials could save 4 days in ICU and hospital length of stay and result in a 14% absolute reduction in mortality at 1 year. Delirium duration was reduced in septic subgroup (unpublished observations) though unchanged in overall study population, indicating that more work is needed perhaps with other interventions to help reduce this important element of organ dysfunction. EW - Adjunctive haloperidol prophylaxis reduces postoperative delirium severity and duration in at-risk elderly patients. Schrader et al.
Link
The Neurologist 2008; 14: 134-7. - Effect of sedation with dexmedetomidine vs Lorazepam on acute brain dysfunction in mechanically ventilated patients. MENDS. Pandharipande et al.
Link
JAMA 2007; 298: 2644-53
The first double blind RCT of alpha-2 agonist dexmedetomidine versus GABA agnonist lorazepam to document reduction in delirium-free/coma-free days and higher likelihood of hitting sedation target. Used the CAM-ICU instrument and RASS scale as validated outcomes instruments. EW - Interventions for preventing delirium in hospitalised patients. Siddiqui et al.
Link
Cochrane review 2007.
Important review from the Cochrane group showing how much work is still needed on this critical area of patient care. Multiple small studies with no clear answers. Despite huge amounts of evidence speaking to the enormous burden and frequency of delirium in hospitalized patients, there is no landmark study to date addressing even the most fundamental question, which is whether or not the currently recommended drug of choice (haloperidol) is helping or hurting our patients. A multicenter study must be designed and conducted to inform clinicians about appropriate pharmacological management of delirium in the critically ill. EW - A multifactorial intervention program reduces the duration of delirium, length of hospitalization, and mortality in delirious patients. Lundstrom et al.
Link
JAGS 2005; 53: 622-628
Patient allocation system with individualised care. mean LOS, delirium, mortality 3.2% vs. 14.5% VJP - A multifactorial intervention to reduce prevalence of delirium and shorten hospital length of stay. Naughton et al.
Link
JAGS 2005; 53: 18-23.
Prevalence 41% to 19% at 9 months, admitted to selective unit, emphasis on improved medication management. VJP - Olanzapine vs haloperidol: treating delirium in a critical care setting. Skrobik et al
Link
ICM 2004; 30: 444-49
First RCT in the ICU of antipsychotics testing typical vs. atypical. No control group. No difference in outcomes. Questions related to the integrity of randomization scheme using odd days method. EW - The effects of targeted multicomponent delirium intervention on postdischarge outcomes for hospitalized older adults. Bogardus et al.
Link
Am J Med 2003; 114: 383-90
Follow up to the NEJM study listed below showing no long-term difference in the Inouye intervention. Further work needed. EW - A mulitcomponent intervention to prevent delirium in hospitalized older patients. Inouye et al.
NEJM 1999; 340: 669-76.
Classic investigation showing that preventive, predominantly non-pharmacological interventions can reduce delirium from ~15% to 9% rate. Not an ICU study, but this study can help design future complex interventions for the ICU. EW - A double-blind trial of haloperidol, chlorpromazine, and Lorazepam in the treatment of delirium in hospitalized AIDS patients. Breitbart et al.
Link
Am J of Psych. 1996; 153: 231-37
Early study on this topic. Problem is that there is not control (placebo) group and these are not ICU patients. EW