Alicia Vasu

American College of Emergency Physicians

BJ Naughton

DE Sinclair

Eillyne Seow

Kanich

Kenneth Heng Wei Jian

Lim Beng Leong

MH Bross

SG Rothrock

Z Kekec

International Journal of Emergency Medicine

English

PubMed

Crossref

Prospective study of patients with altered mental status: clinical features and outcome

Springer - Publisher Connector

ORIGINAL ARTICLE
Prospective study of patients with altered mental status:
clinical features and outcome
Lim Beng Leong & Kenneth Heng Wei Jian &
Alicia Vasu & Eillyne Seow
Received: 29 June 2008 /Accepted: 20 July 2008 / Published online: 24 September 2008
# Springer-Verlag London Ltd 2008
Abstract
Aims Patients with altered mental status (AMS) present
commonly to the Emergency Department (ED). The aim of
this prospective study is to identify the various clinical
features of this diverse group of patients and trace their
outcomes. This will allow clinicians to be aware of the
natural history of the symptom complex and the difficulties
in managing them.
Methods In this prospective observational study, we
recruited patients aged 18 and above diagnosed with AMS
at Tan Tock Seng Hospital ED from December 2006 to
October 2007. This is an urban ED. Demographic, clinical,
radiology, laboratory data, final diagnosis and length of stay
were collected from their entry into the ED till discharge or
demise using the ED’s and inpatient electronic records.
Results From December 2006 to October 2007, 967
patients with a mean age of 66.5 years diagnosed with
AMS were recruited into our study. The total number of CT
scans done during the study period was 674, of which 246
(37%) were abnormal and 428 (63%) were normal. The
mean hospital length of stay was 11.6 days. Patients with
abnormal CT results stayed longer than those whose results
were normal (median of 9 days versus median of 6 days).
The three most common causes of AMS in our study
population were of neurological (34.4%), infectious
(18.3%) and metabolic (12%) aetiologies. Overall, 106
(11%) patients died during hospitalisation; 36 (33.9%) and
39 (36.8%) deaths were attributed to ischaemic stroke and
haemorrhagic stroke, respectively.
Conclusions AMS remains a symptom complex that carries
a significant length of hospital stay and mortality. The most
common causes of AMS are those that require timely
intervention and are highly treatable. This study will provide
insight into proper allocation of resources to manage this
group of patients, from triaging to investigations and
treatment at the ED and inpatient levels.
Keywords Altered mental status . Outcome
Introduction
Altered mental status (AMS) is a symptom complex that
continually poses a great challenge in the Emergency
Department (ED). It has various causes and treatments,
many of which require timely intervention [1].
The purpose of the study is to provide insight into the
clinical, demographical features as well as the outcome of
patients presenting to our ED through to their entire length
of stay in the hospital.
We aim to provide clinicians with the necessary
information regarding the epidemiology of this symptom
Int J Emerg Med (2008) 1:179–182
DOI 10.1007/s12245-008-0049-8
The views expressed in this paper are those of the author(s) and not
those of the editors, editorial board or publisher.
L. B. Leong (*) :K. H. W. Jian : E. Seow
Tan Tock Seng Emergency Department,
11, Jalan Tan Tock Seng,
Singapore 308433, Singapore
e-mail: Beng_Leong_Lim@ttsh.com.sg
K. H. W. Jian
e-mail: khengwj@gmail.com
E. Seow
e-mail: eillyne_seow@ttsh.com.sg
A. Vasu
Biomedical Sciences,
Singapore, Singapore
e-mail: alicia.vasu@gmail.com
complex in an urban ED. This will guide future allocation
of resources in the most cost-effective manner in the
management of patients with AMS.
Methods
A prospective observational study was conducted on all
patients presenting to the ED with altered mental state
(AMS) from December 2006 to October 2007 at Tan Tock
Seng Hospital (TTSH), Singapore. TTSH is an urban ED
with an annual census of 154,000 in 2007 and receives
patients from all regions in the country.
A pilot study using retrospective data in our department
together with review of the literature [2–4] formed the basis
of an AMS data collection form that was prospectively
completed by the ED doctors for all recruited patients.
AMS was defined as a state of drowsiness, unrespon-
siveness, sudden behavioural change, disorientation or
confusion, agitation or hallucination.
All patients above 18 years of age who presented with
AMS at triage in the ED were included in the study.
Patients referred from another healthcare facility for whom
their referring physicians had already worked out the cause
for AMS were excluded from the study. Similarly, patients
who had sustained major trauma from motor vehicle
crashes or falls from heights were excluded. This study
was approved by the National Healthcare Group Research
Ethics Committee.
Patients were managed by attending emergency physi-
cians (EPs) and ward specialists. The management and the
utilisation of specific investigations like computer tomo-
graphic (CT) scans were based on the discretion of the
attending doctors.
Demographic, clinical, radiological and laboratory data
of each patient throughout the stay in the hospital from
entry into the ED till discharge or demise were collected.
ED electronic notes, AMS forms, inpatient medical records,
radiology films and reports were reviewed.
All statistical analyses were performed using SPSS 13.0
(SPSS Inc., IL). All tests were conducted at the 5% level of
significance, with odds ratios (OR) and corresponding 95%
confidence intervals (CI) reported where applicable.
Results
From December 2006 to October 2007, 967 patients with
AMS were recruited into our study. The annual attendance
for 2007 was 154,000. Table 1 describes the baseline
demographic data for the patients recruited. The majority of
patients (60%) were 65 years and above. AMS patients
presented most commonly (67%) within the first 24 h of
onset of symptom with drowsiness as the most common
presenting complaint (51%).
The frequency of AMS increases with age in a non-
Gaussian manner with a mode of 75 years and mean of
66.5 years (SD of 18.1).
After the initial screening investigations of an electro-
cardiogram and capillary blood sugar, the subsequent
management was based on the discretion of the attending
emergency physician or inpatient specialists. Of note, 674
patients (70%) received CT scan of the brain, of which 394
(58%) were performed at the ED and the rest at the ward
level. Of all CT scans performed, 246 (36%) were reported
to be abnormal; 135 were found to have ischaemic stroke,
106 to have haemorrhagic stroke and 5 to have tumours.
All patients were admitted to either the medical,
neurology or neurosurgical units based on the attending
EP’s provisional diagnosis.
The various definitive causes of AMS upon discharge or
demise are demonstrated in Table 2.
In the younger age group of 16–64 years, the various
AMS causes were more evenly distributed with neurolog-
ical, psychiatric and toxicological aetiologies as relatively
Table 1 Demographics of study population (N=967)
Variables Total
Gender
Males 459 (48%)
Ethnicity
Chinese 747 (77%)
Malay 106 (11%)
Indian 86 (9%)
Others 28 (3%)
Age range (in years)
65 and above 581 (60%)
Type of AMS
Drowsiness 331 (51%)
Sudden behavioural change 180 (27%)
Unresponsiveness 248 (37%)
Disorientated/confused 199 (30%)
Agitation 51 (8%)
Hallucination 41 (6%)
Duration of AMS
Acute (24 h) 647 (67%)
Subacute (less than 7 days) 215 (22%)
Chronic (more than 7 days) 105 (11%)
Concurrent medications
Benzodiazepine 55 (6%)
Tricyclic anti-depressant 8 (1%)
SSRIs 54 (6%)
Anti-psychotics 66 (7%)
Anti-coagulant 34 (4%)
Anti-platelet 121 (13%)
Alcohol 53 (6%)
180 Int J Emerg Med (2008) 1:179–182
more common. In the older age group of >65 years,
neurological, infectious and metabolic aetiologies were
more common. In the latter group of patients, the sources
of infection include urinary tract infection (36%), pneumo-
nia (22%) and sepsis (27%).
The outcomes of these AMS patients were followed up
prospectively. The mean hospital length of stay was
11.6 days (median 7 days; range 1–137 days). Patients
with abnormal CT results stayed longer than those whose
results were normal (median of 9 days; range 1–137 days
compared with median of 6 days; range 1–114 days;
p=0.001).
Overall, 106 (11%) patients died during hospitalisation;
36 (33.9%) and 39 (36.8%) deaths were attributed to
ischaemic stroke and haemorrhagic stroke, respectively.
We investigated the causes of mortality between the
younger (18–64 years) and older (>65 years) subgroups. The
majority of younger patients died from haemorrhagic stroke,
while in older patients, mortality is distributed amongst
ischaemic stroke (38%), haemorrhagic stroke (30%) and
others (chiefly infection; 20%). This is demonstrated in
Table 3.
Table 4 illustrates the outcomes of the survivors. The
majority of patients were discharged to primary care (76%)
or the hospital’s outpatient clinics (12%). A small minority
of patients were transferred to step-down care comprising
of nursing homes (2.4%) and rehabilitation hospitals
(3.8%).
Discussion
AMS remains a diagnostic challenge in the Emergency
Department. It has a multitude of possible aetiologies.
Acute onset of AMS within 24 h is the most common
reason for seeking consultation at the ED. Among the
various aetiologies, neurological causes are the most
common, and our findings agree with what had been
reported by Kanich et al. [5]. Futhermore, this has
important downstream implications for triaging and cost-
effective use of investigations, especially CT scan of the
brain [6, 7].
We have demonstrated that AMS is a symptom complex
that carries a high admission rate, a long length of stay and
significant mortality rate (11% in our study, and this agrees
with what is reported by Zeynep Kekec et al. [8]). Our
study has also demonstrated that the causes of AMS vary
amongst the different age groups. Although it is not as
Table 2 Causes of AMS in patients aged 16–64 (N=392) and >65
(N=600)*
Cause of death 18–64 years 65 years
and above
Neurological 11.7% 22.7%
Infectious 4.3% 14.0%
Metabolic 4.3% 7.8%
Toxicological 6.0% 2.2%
Cardiac 1.5% 5.9%
Organ specific impairment 5.0% 1.7%
Psychiatric 1.1% 1.7%
Trauma 1.0% 1.4%
Miscellaneous 3.2% 4.7%
*N>967 as some patients were assessed to have more than one cause
of AMS
Table 3 Distribution of causes of mortality between two age subgroups
Cause of death 18–64 years old
(n=30; 28%)
65 years and above
(n=76; 72%)
p value
Trauma 1 (3.3%) 5 (6.6%) 0.673
Cardiac 1 (3.3%) 4 (5.3%) 1.000
Others* 5 (16.7%) 15 (19.7%) 0.790
Ischaemic stroke 7 (23.3%) 29 (38.2%) 0.176
Haemorrhagic stroke 16 (53.3%) 23 (30.3%) 0.043
*Others include infective causes or combination of infective and CVA; trauma includes relatively minor mechanisms like falls
Table 4 Distribution of outcomes of surviving AMS patients
(N=861)
Outcome Number
Discharge to primary care 651
Discharge to nursing home 21
Transfer to rehabilitation hospital 33
Discharge to hospital outpatient clinic 107
Discharged against medical advice 26
Missing data* 23
*Missing data includes those with incomplete data or those whose
disposition was not available at time of conclusion of study
Int J Emerg Med (2008) 1:179–182 181
common as other complaints like chest pain, it is one that
challenges the physician’s judgment, and time is required in
the evaluation of such patients. This also impacts on
resource utilisation within the hospital.
AMS will continue to be a diagnostic challenge for EPs
worldwide as the world’s population ages. Appropriate
management of AMS in geriatric patients in the ED requires
substantial staff time, training, resources and commitment. In
addition, EP’s satisfaction in management of this group of
patients who require prolonged clinician time will also be
affected in this high-stress environment [9].
Conclusion
AMS is and will be a growing symptom complex that
prompts caregivers to consult the public healthcare system
particularly in the context of a rapidly aging population in
many countries.
The common and important causes of AMS require
timely diagnosis, intervention and are largely amenable to
treatment. AMS remains a symptom that carries a significant
degree of morbidity and mortality, especially in elderly
patients with neurological aetiologies.
Future research should be targeted to exploring cost-
effective ways to triage, investigate and manage this symptom
complex.
Conflicts of interest None.
References
1. American College of Emergency Physicians (1999) Clinical policy
for the initial approach to patients presenting with altered mental
status. Ann Emerg Med 33(2):251–281, Feb
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cognitive impairment in older adults in an emergency department.
Ann Emerg Med 25:751–755
3. Bross MH, Tatum NO (1994) Delirium in the elderly patient. Am
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5. Kanich et al (2002) Altered mental status: evaluation and etiology
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I, Dr. Lim Beng Leong, am currently working as an associate
consultant in Tan Tock Seng Emergency Department, an urban ED
in Singapore. I have done a retrospective study of AMS patients that
was used as a pilot for the current study. My other research interests
are in emergency cardiac care, and I am currently working on projects
of pre-hospital ECGs and their impact on mortality and baseline ECG
features that are important to recognize at triage, such as Wellen’s and
Brugada ECGs.
182 Int J Emerg Med (2008) 1:179–182


Altered mental status: evaluation and etiology in the ED.

Cranial computed tomography of adult patients without a recent history of head trauma: prospective analysis. Acad Emerg Med 4:654–661

Delirium and other cognitive impairment in older adults in an emergency department.

Delirium in the elderly patient.

et al (2008) Analysis of altered mental status in Turkey.

Kanich WAltered mental status: evaluation and etiology in the ED.

Scans: emergency department utilization.

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Prospective study of patients with altered mental status: clinical features and outcome

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