Lp-PLA₂ activity and mass for prediction of incident abdominal aortic aneurysms: A prospective longitudinal cohort study

Background and aims The pathogenesis of abdominal aortic aneurysm (AAA) shares several common pathways with atherosclerosis. Prospective clinical plasma biomarker studies in AAA have been hampered by the need for very large cohorts and long follow-up time. Methods We analyzed a prospective longitudinal cohort of middle-aged individuals from the cardiovascular cohort of the Malmö Diet and Cancer study (n = 5551; 1991-94). The plasma biomarkers lipoprotein-associated phospholipase A2 (Lp-PLA₂ activity and mass), proneurotensin and C-reactive protein, and conventional risk factors at baseline were measured in patients with incident AAA during follow-up, and compared to individuals without a diagnosis of AAA. Subjects were followed until December 31st, 2013. Multivariable analyses were expressed in terms of hazard ratios (HR) per 1 standard deviation increment of each respective log-transformed plasma biomarker in the Cox proportional hazard models. Results Cumulative incidence of AAA was 1.5% (men 2.9%, women 0.5%) during a median follow-up period of 20.7 years. Overall, 84 individuals had an incident AAA, of whom 22 (26.2%) were operated on and 16 (19.0%) had ruptured. Mean age of individuals with incident AAA was 59.7 years at study entry and AAA was diagnosed on average 14 years later. When adjusting for age, gender, smoking, body mass index, hypertension, and diabetes mellitus, Lp-PLA₂ activity (HR 1.40; 95% CI 1.15–1.72) and Lp-PLA₂ mass (HR 1.23; 95% CI 1.00–1.51) were independently associated with incident AAA. Conclusions The plasma biomarkers Lp-PLA₂ activity and mass were markers of AAA risk and this implies that AAA is an athero-thrombotic related disease.