title: Meta-analysis and meta-regression analysis of biomarkers for abdominal aortic aneurysm.
abstract: BACKGROUND
  Many studies have investigated the systemic and local expression of biomarkers in patients with abdominal aortic aneurysm (AAA). The natural history of AAA varies between patients, and predictors of the presence and diameter of AAA have not been determined consistently. The aim of this study was to perform a systematic review, meta-analysis and meta-regression of studies comparing biomarkers in patients with and without AAA, with the aim of summarizing the association of identified markers with both AAA presence and size.
  
  
  RESULTS
  Literature review identified 106 studies suitable for inclusion. Meta-analysis demonstrated a significant difference between matrix metalloproteinase (MMP) 9, tissue inhibitor of matrix metalloproteinase 1, interleukin (IL) 6, C-reactive protein (CRP), α1-antitrypsin, triglycerides, lipoprotein(a), apolipoprotein A and high-density lipoprotein in patients with and without AAA. Although meta-analysis was not possible for MMP-2 in aortic tissue, tumour necrosis factor α, osteoprotegerin, osteopontin, interferon γ, intercellular cell adhesion molecule 1 and vascular cell adhesion molecule 1, systematic review suggested an increase in these biomarkers in patients with AAA. Meta-regression analysis identified a significant positive linear correlation between aortic diameter and CRP level.
  
  
  CONCLUSIONS
  A wide variety of biomarkers are dysregulated in patients with AAA, but their clinical value is yet to be established. Future research should focus on the most relevant biomarkers of AAA, and how they could be used clinically.
authors.affiliation: Department of Cardiovascular Sciences, University of Leicester, Leicester, UK.
authors.forename: P W
authors.initials: PW
authors.lastname: Stather
authors.forename: D A
authors.initials: DA
authors.lastname: Sidloff
authors.forename: N
authors.initials: N
authors.lastname: Dattani
authors.forename: V J
authors.initials: VJ
authors.lastname: Gokani
authors.forename: E
authors.initials: E
authors.lastname: Choke
authors.forename: R D
authors.initials: RD
authors.lastname: Sayers
authors.forename: M J
authors.initials: MJ
authors.lastname: Bown
mesh_terms: D017544:Aortic Aneurysm, Abdominal / Q000175:diagnosis*; D001025:Aortitis / Q000175:diagnosis; D015415:Biomarkers / Q000378:metabolism*; D004798:Enzymes / Q000378:metabolism; D006801:Humans; D050356:Lipid Metabolism / Q000502:physiology; D008055:Lipids / Q000032:analysis; D011506:Proteins / Q000378:metabolism; D012044:Regression Analysis
chemical_list: D015415:Biomarkers; D004798:Enzymes; D008055:Lipids; D011506:Proteins