Prognostic value of apolipoprotein E epsilon4 allele in patients with traumatic brain injury: a meta-analysis and meta-regression.
OBJECTIVE
Current scientific evidence suggests that the apolipoprotein E epsilon4 (APOE4) allele may be associated with a good prognosis for patients with traumatic brain injury (TBI); however, many existing studies have yielded inconclusive results. This meta-analysis aims to obtain a more precise estimation of the association between APOE4 allele and prognosis of TBI patients.


METHODS
A literature search of PubMed, Embase, Web of Science, Cochrane Library, CISCOM, CINAHL, Google Scholar, CNKI and CBM databases was conducted for articles published before July 1st, 2013. Crude odds ratios (OR) with 95% confidence intervals (CI) were calculated.


RESULTS
Thirteen cohort studies were included with a total of 662 TBI patients with APOE4 (+) and 1614 TBI patients with APOE4 (-). The meta-analysis results revealed that the APOE4 allele was associated with a poor prognosis in TBI patients (OR=0.68, 95% CI: 0.48-0.96, p=0.027). Subgroup analysis by ethnicity indicated that TBI patients with APOE4 (+) had a worse prognosis than those with APOE4 (-) in Asian populations (OR=0.46, 95% CI: 0.21-0.99, p=0.046), but not in Caucasian populations (OR=0.75, 95% CI: 0.53-1.08, p=0.120). A further subgroup analysis by TBI grade showed that the APOE4 allele was associated with poor prognosis in severe TBI patients (OR=0.43, 95% CI: 0.21-0.87, p=0.020). However, there was no evidence for any association between the APOE4 allele and poor prognosis in patients with other grades of TBI (all p>0.05).


CONCLUSIONS
The current meta-analysis indicates that the APOE4 allele may be associated with a poor prognosis in severe TBI patients and in Asian populations. The APOE4 allele may be used as a biomarker in predicting the prognosis of TBI patients.
1 Department of Neurosurgery, Institute of Surgery Research, Daping Hospital, Third Military Medical University , YuZhong District, Chongqing, People's Republic of China .
Shi
S
Zeng
Jian-Xin
JX
Jiang
Min-Hui
MH
Xu
Lun-Shan
LS
Xu
Guang-Jian
GJ
Shen
An-Qiang
AQ
Zhang
Xu-Hui
XH
Wang
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D053327:Apolipoprotein E4 / Q000235:genetics*; D015415:Biomarkers / Q000032:analysis; D001930:Brain Injuries / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics* / Q000628:therapy; D002648:Child; D002675:Child, Preschool; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D012044:Regression Analysis; D055815:Young Adult
D053327:Apolipoprotein E4; D015415:Biomarkers