Three year survival rates did not differ between patients with Alzheimer's disease and those with dementia with Lewy bodies
Walker Z, Allen RL, Shergill S, et al. Three years survival in patients with a clinical diagnosis of dementia with Lewy
bodies. Int J Geriatr Psychiatry 2000 Mar;15:267-73
QUESTION: In patients with Alzheimer's disease (AD) and in those with dementia with
Lewy bodies (DLB), do mortality rates and duration of illness differ?
Design
Inception cohort followed up for 3 years.0
Setting
An old age psychiatry unit in the UK.
Patients
114 patients with a clinical diagnosis of AD using ICD.10
criteria or a diagnosis of DLB using McKeith and Byrne
criteria. Eight patients (7%) were lost to follow up.
Assessment of prognostic factors
Case notes of all patients were reviewed to determine the
original diagnosis, and the dates of symptoms onset and
first presentation to psychiatric services.
Main outcome measures
Mortality rate and duration of illness were determined
by reviewing case notes, hospital files, and general practitioner records.
Main results
Of the 106 patients followed, 43 originally had a diagnosis of AD, 32 had DLB, 30 had a diagnosis of vascular de.
mentia, and 1 was diagnosed with alcoholic dementia. At
3 years, 64 patients (60%) had died. More patients died
in the vascular dementia group (87%) than in the DLB
group (53%) and the AD group (49%) (P < 0.003). No
difference existed in the mortality rate between DLB and
AD patients. The mean survival time from first onset of
symptoms until death was 5.5 years in the DLB group
and 5.6 years in the AD group, with no statistically
significant difference between the groups. The mean
survival time from presentation to psychiatric services
until death was 3.5 years in the DLB group and 3.1 years
in the AD group, with no statistically significant
difference between the groups.
Conclusion
The 3 year survival rate did not differ between patients
with Alzheimer's disease and those with dementia with
Lewy bodies.
COMMENTARY
Cortical DLB is a relatively common cause of dementia, pos.
sibly accounting for up to 20% of cases, and should no
longer be regarded as an esoteric rarity. The clinical characteristics include fluctuating cognitive ability, prominent
visual hallucinations, and movement disorders including
parkinsonism. Does distinguishing DLB from other causes
of dementia have any implications for the clinician, patient,
or carer? Yes. Although Walker et al found no difference in
the prognosis of DLB compared with AD, there are other
characteristics of DLB that render diagnosis imperative. The
visual hallucinations may tempt unwary clinicians to
prescribe antipsychotic medication. This is likely to make the
movement disorder worse, increase the risk of falls, and
increase mortality. 1 Some evidence is emerging that these
symptoms may be helped by cholinesterase inhibitors, but
further evaluation of this is awaited.
For the patient, the fluctuating cognitive ability may be
profound (I once saw a patient with DLB who alternated
between doing the Times newspaper crossword and sitting in
a semi.vegetative state). The opportunity to understand the
basis of this may be welcome (provided the clinician wants to
go down the road of discussing the diagnosis with the
patient). Carers may find the constellation of symptoms,
especially the hallucinations, bewildering and frightening,
and again, a label and explanation may be helpful.
This study by Walker et al has other important messages.
Firstly, in this sample at least, clinical diagnosis of DLB was
as common as vascular dementia. Secondly, the median survival time after onset of symptoms was 5.3 years,
underpinning the fact that this is a chronic disease that may
have a major effect on carers and services as well as our
patients. Any study that heightens awareness of this form of
dementia and contributes to our understanding of the
disease is welcome.
James Warner, Imperial College, London
- 1 McKeith IG, Fairbairn AF, Perry RH, et al. Neuroleptic sensitivity in patients with senile dementia of Lewy body type. BMJ 1992;305:673.8.
studentBMJ 2001;09:1-42 February ISSN 0966-6494
