Circulating matrix metalloproteinase-9 concentrations and abdominal aortic aneurysm presence: a meta-analysis.

To summarize the present evidence for an association between matrix metalloproteinase-9 (MMP-9) and abdominal aortic aneurysm (AAA) presence, we performed a meta-analysis of case-control studies that compared circulating MMP-9 concentrations between patients with AAA and subjects without AAA. MEDLINE database was searched to identify all case-control studies. For each study, data regarding serum or plasma MMP-9 concentrations in both the AAA and control groups were used to generate standardized mean differences (SMDs) and 95% confidence intervals (CIs). Study-specific estimates were combined using inverse variance-weighted average of logarithmic SMDs in both fixed- and random-effects models. Our search identified eight eligible studies including 580 patients with AAA and 258 subjects without AAA. Pooled analysis demonstrated significantly higher circulating MMP-9 concentrations in the AAA group than those in the control group in random-effect models (SMD, 0.70; 95% CI, 0.23-1.17; P=0.004). There was significant study heterogeneity of results (P<0.00001) but no evidence of significant publication bias (P=0.1376). We found that, based on a systematic review and meta-analysis, circulating MMP-9 concentrations are higher in patients with AAA than those in subjects without AAA. Higher circulating MMP-9 concentrations are associated with AAA presence.