Lp(a) levels associated with lower-limb PAD
MedWire News: Lipoprotein (Lp)(a) is independently associated with the presence of peripheral arterial disease (PAD) in the lower limbs, an Italian study suggests.
However, the researchers call for prospective studies in larger populations to establish whether Lp(a) is a true risk factor for the development of PAD, as it is known to be for coronary heart disease and stroke.
Stefano Volpato (University of Ferrara) and co-workers analyzed data from the Invecchiare in Chianti Study, an Italian community-based study of 1002 men and women aged 60 years or above.
All participants had their ankle-brachial index (ABI) measured at baseline and again 6 years later, with PAD being defined as an index <0.90. In all, 125 participants had PAD at baseline and a further 57 developed PAD during follow-up.
Volpato’s group identified a stepwise increase in the likelihood of prevalent PAD across quartiles of Lp(a) distribution. After adjustment for multiple confounders (including inflammation), the odds ratio for PAD was 1.83 for those in the highest Lp(a) quartile (32.9–175.9 mg/dl) versus the lowest quartile (0.0–3.5 mg/dl).
The association was even stronger when PAD was defined as an ABI below 0.70, as a proxy for more severe disease. In this analysis, the adjusted odds ratio rose to 3.80 for participants in the highest versus the lowest Lp(a) quartile.
Similarly, the likelihood of incident PAD over 6 years of follow-up rose across quartiles of Lp(a), such that the adjusted odds ratio was 1.52 for those in the highest versus the lowest quartile. This difference was not statistically significant, however.
Finally, the authors report that there was a graded relationship between Lp(a) and ABI score, “suggesting a potential dose-response relation with PAD severity.”
Noting that Lp(a) may act as an acute-phase reactant and that Lp(a) levels increase after acute clinical events, they team concludes: “Different biologic mechanisms, including atherogenic and thrombogenic activities, support a role of Lp(a) in the development of atherosclerosis and its clinical complications.
They add: “Lp(a) is an independent lower-limb PAD correlate in the cross-sectional evaluation, but further prospective studies in larger populations, with longer follow-up and more definite lower-limb PAD ranking, might be needed to establish a longitudinal association.”
The study appears in the American Journal of Cardiology.
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By Joanna Lyford