Association of high sensitivity C-reactive protein and abdominal aortic aneurysm: a meta-analysis and systematic review.

Objective: To evaluate the association of high sensitivity C-reactive protein (hsCRP) with the presence of abdominal aortic aneurysm (AAA).

Methods: Medline, Cochrane, Embase, and Google Scholar databases were searched until 22 June 2016 using the keywords predictive factors, biomarkers, abdominal aortic aneurysm, prediction, high sensitivity C-reactive protein, and hsCRP. Prospective studies, retrospective studies, and cohort studies were included.

Results: Twelve case-control studies were included in the meta-analysis with a total of 8345 patients (1977 in the AAA group and 6368 in the control group). The pooled results showed that AAA patients had higher hsCRP value than the control group (difference in means = 1.827, 95% CI = 0.010 to 3.645, p = .049). Subgroup analysis found AAA patients with medium or small aortic diameter (<50 mm) had higher hsCRP plasma levels than the control group (difference in means = 1.301, 95% CI = 0.821 to 1.781, p < .001). In patients with large aortic diameter (≥50 mm), no difference was observed in hsCRP levels between the AAA and control groups (difference in means = 1.769, 95% CI = -1.387 to 4.925, p = .272). Multi-regression analysis found the difference in means of hsCRP plasma levels between AAA and control groups decreased as aortic diameter increased (slope = -0.04, p < .001), suggesting that hsCRP levels may be inversely associated with increasing aneurysm size.

Conclusions: Our findings suggest that hsCRP levels may possibly be used as a diagnostic biomarker for AAA patients with medium or small aortic diameter but not for AAA patients with large aortic diameter. The correlation between serum hsCRP level and AAA aneurysm is not conclusive due to the small number of included articles and between-study heterogeneity.