We read with great interest a study by Golledge et al demonstrating no association between serum low-density lipoprotein (LDL) concentrations and abdominal aortic aneurysm (AAA) but a consistent association between low serum high-density lipoprotein (HDL) concentrations and the presence of a small AAAs in a large population prone to aortic dilation (i.e., men aged ≥65 years). Although a number of studies compared serum HDL or LDL concentrations between patients with AAAs and control subjects, no meta-analysis has been conducted to date to the best of our knowledge. To summarize the present evidence for an association between serum HDL or LDL concentrations and AAA presence, we herein report a meta-analysis of studies from which we can abstract mean and SD serum HDL or LDL concentrations.
To identify all studies that compared serum HDL or LDL concentrations between patients with AAAs and control subjects, public-domain databases, including Medline and EMBASE, were searched using Web-based search engines (PubMed, Ovid). Text keywords included “high-density lipoprotein,” “HDL,” “low-density lipoprotein,” “LDL,” and “abdominal aortic aneurysm.” Studies considered for inclusion met the following criteria: the design was a case-control or cross-sectional study; the study population was patients with AAAs and control subjects, and the study included ≥50 subjects (patients and controls combined); and main outcomes included the mean and SD serum HDL or LDL concentrations in the AAA and control groups.
Our search identified 9 studies that compared serum HDL or LDL concentrations between patients with AAAs and control subjects. These included 6 studies cited in the report of Golledge et al (their references 1 to 6) and 3 additional studies. For each study, data regarding serum HDL or LDL concentrations in the AAA and control groups were used to generate mean differences and 95% confidence intervals. Pooled analysis of the 9 studies (representing 1,057 patients with AAAs and 11,349 control subjects) demonstrated significantly lower serum HDL concentrations in the AAA group than in the control group (random-effects mean difference −0.14 mmol/L, 95% confidence interval −0.21 to −0.08 mmol/L, p <0.0001, p for heterogeneity <0.00001; Figure 1 ). Pooled analysis of the 8 studies (representing 720 patients with AAAs and 5,300 control subjects) demonstrated no significant differences between serum LDL concentrations in the AAA group and those in the control group (random-effects mean difference 0.14 mmol/L, 95% confidence interval −0.04 to 0.31 mmol/L, p = 0.13, p for heterogeneity <0.00001; Figure 1 ).
