In patients who survive traumatic brain injury
(TBI), what is the relation between the apolipoprotein E (APOE) ε4
allele and outcome?
Cohort analytic study with 6-8 months of follow up.
A hospital department for brain injury and rehabilitation and
an outpatient rehabilitation clinic in Israel.
69 patients (mean age 36 y, 75% men) with blunt trauma.
Patients with penetrating injuries or anoxic brain damage were
excluded.
APOE genotype, Glasgow Coma Scale score, duration of
unconsciousness, admission to an intensive care unit (ICU) in hospital,
age, and duration of education.
Independence in activities of daily living (ADL), cognitive and
behavioural abnormalities, dysarthria, dysphasia, epilepsy, and overall
function. A good outcome was defined as no dysarthria, behavioural
abnormalities, or dysphasia; no severe cognitive abnormalities; and the
ability to live independently. Outcome assessors were blinded to APOE
status.
Patients who were unconscious for >7 days were more likely to
have an APOE ε4 allele (78% v 38%,
p=0.001). Fewer patientswith an APOE ε4 allele had a good
outcome than those without such an allele (4%
v 31%, p=0.006, odds ratio [OR] 0.1, 95%
CI 0.0 to 0.7). More patients with an APOE ε4 allele had dysarthria
(63% v 33%, p=0.02, OR 3.4, CI 1.1 to
10.7). No statistically significant associations existed between the
presence of an APOE ε4 allele and independence in ADL, behavioural
abnormalities, severe cognitive abnormalities, dysarthria, or epilepsy.
In multivariate analysis, the independent risk factors for an
unfavourable outcome were the presence of an APOE ε4 allele (p=0.02),
increasing age (p=0.01), and being unconscious for >7 days (p=0.02)
(table).
In patients who survived traumatic brain injury, those having
an apolipoprotein ε4 allele were more likely to be unconscious for
>7 days. At 6 months, independent risk factors for poor outcome were
presence of the APOE ε4 allele, older age, and unconsciousness for
>7 days.
Psychiatrists working in rehabilitation settings and in
general hospitals frequently have to assess the prognosis of patients
with TBI. This task is a challenging one because long term outcome
depends on an interaction of susceptibility to injury, severity of
insult, and capacity to repair and regenerate. To date, the prediction
of long term outcome has relied largely on measures of short term
outcome, such as duration of unconsciousness or post-traumatic amnesia,
or coma score. 1 Risk factors that are not themselves
aspects of outcome offer hope of more accurate and earlier prediction.
Such factors are likely to relate to susceptibility to injury or to
repair.
1 Asikainen
I, Kaste M, Sarna S. Brain Inj
1998;12:95-107.
Question
Design
Setting
Participants
Assessment of risk factors
Main outcome measures
Main results
Conclusions
Risk factors
Adjusted odds ratio (95%
CI)* APOE ε4 allele present 13.9 (1.5 to 134.0)
Age 1.1 (1.0 to 1.2) per year Unconscious for >7
days 7.6 (1.4 to 40.0) Commentary
APOE ε4 allele, age, and duration of
unconsciousness were associated with unfavourable outcomes in traumatic
brain injury