title: Serum ubiquitin C-terminal hydrolase L1 as a biomarker for traumatic brain injury: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Serum ubiquitin C-terminal hydrolase L1 (UCH-L1) has been proposed as a biomarker of traumatic brain injury (TBI). However, previous studies on levels of UCH-L1 in serum remain inconsistent. This systematic review and meta-analysis were conducted on observational studies that reported the association between serum UCH-L1 levels and TBI.
  
  
  METHODS
  Studies were identified by searching PubMed and ISI Web of Science up to February 2015. For the continuous outcomes, we calculated the weighted mean difference and 95% confidence interval. The statistical analysis was performed by RevMan 5.1 and Stata 12 software. Only case-control studies were included if they had data on serum UCH-L1 levels in TBI patients and healthy controls. Funnel plot and Egger's regression test were applied to assess the potential publication bias.
  
  
  RESULTS
  Of the 145 selected studies, 11 observational studies (including 9 case-control and 2 case-crossover studies) met the selection criteria, containing a total of 1138 TBI cases and 1373 controls. Finally, 5 case-control studies (including 673 TBI and 1004 controls) were eligible for the present meta-analysis. The results of our study showed that there was a significant increase in serum UCH-L1 levels in patients with TBI compared to controls (weighted mean difference, 0.96; 95% confidence interval, 0.31-1.61; P = .004).
  
  
  CONCLUSIONS
  In conclusion, TBI cases had higher serum UCH-L1 concentrations than matched controls. This reinforces the conceptualization of UCH-L1 as a potential biomarker of TBI.
authors.affiliation: Department of Orthopaedics, the Xinhua Hospital Affiliated of Dalian University, Dalian, 116021, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Life Science and Technology, Dalian University, Dalian 116622, PR China.
authors.forename: Chao
authors.initials: C
authors.lastname: Yu
authors.affiliation: Liaoning Provincial Key Laboratory of Cerebral Diseases, Institute for Brain Disorders, Dalian Medical University, Dalian, 116044, PR China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Liaoning Provincial Key Laboratory of Cerebral Diseases, Institute for Brain Disorders, Dalian Medical University, Dalian, 116044, PR China. Electronic address: liyuyuan831221@163.com.
authors.forename: Yuyuan
authors.initials: Y
authors.lastname: Li
mesh_terms: D015415:Biomarkers / Q000097:blood; D001930:Brain Injuries / Q000097:blood* / Q000175:diagnosis; D006801:Humans; D064887:Observational Studies as Topic; D011379:Prognosis; D043222:Ubiquitin Thiolesterase / Q000097:blood*
chemical_list: D015415:Biomarkers; D043222:Ubiquitin Thiolesterase