Lipoprotein(a) and abdominal aortic aneurysm risk: The Atherosclerosis Risk in Communities study

Background and aims: No prospective study has investigated whether elevated lipoprotein(a) concentrations are associated with an increased risk of abdominal aortic aneurysm (AAA). We aimed to prospectively investigate this association.

Methods: In 1987-1989, the Atherosclerosis Risk in Communities study measured plasma lipoprotein(a) in 13,683 participants aged 45-64 years, without a history of AAA surgery. We followed them for incident, clinical AAA events through 2011.

Results: During the 272,914 person-years of follow-up, over a median of 22.6 years, we documented 505 incident AAA events. The age-, sex-, and race-adjusted model showed that individuals in the highest quintile of plasma lipoprotein(a) had an increased risk of AAA. Further adjustment for the other potential confounding factors, including other plasma lipids (high- and low-density lipoprotein cholesterol and triglyceride concentrations), attenuated the association, but individuals in the highest versus lowest quintile of plasma lipoprotein(a) still had a significantly increased risk of AAA [hazard ratio (95% confidence interval): 1.57 (1.19-2.08)]. Interaction testing suggested no difference in the associations for whites and African Americans (p for interaction = 0.96). A restricted cubic spline analysis demonstrated a positive dose-response relation of plasma lipoprotein(a) with AAA, with a steep increase in AAA risk above the 75th percentile (p for overall association = 0.0086, p for non-linear association = 0.097).

Conclusions: In this population-based cohort study, elevated lipoprotein(a) concentrations were independently associated with an increased risk of AAA. The association reflected a threshold of increased AAA risk at high lipoprotein(a) concentrations, rather than a steady monotonic association.