Lipoprotein (a) and venous thromboembolism in adults: a meta-analysis

BACKGROUND: Lipoprotein (a) [Lp(a)], a low-density lipoprotein particle linked to apolipoprotein (a), has been recently demonstrated to be an independent risk factor for arterial vascular diseases. However, despite increasing evidence of the association between high Lp(a) and arterial thrombotic diseases, few and conflicting results on the association between high Lp(a) levels and venous thromboembolism have been obtained. The aim of this article is to systematically examine the published data on the association between high Lp(a) levels and venous thromboembolism. METHODS: A systematic search of all publications listed in the electronic databases (Medline, EMBASE, Web of Science, and The Cochrane Library) up to November 2006, using keywords in combination both as MeSH terms and text words, was conducted. RESULTS: Six case-control studies were included, incorporating 1826 cases of venous thromboembolism and 1074 controls. The summary odds ratios of included case-control studies under a fixed-effects model showed a statistically significant association between Lp(a) levels >300 mg/ L and venous thromboembolism: 1.87, 95% confidence interval (CI), 1.51-2.30; P <.0001. Furthermore, a random-effects model, which accounts for the interstudy variation, yielded a similar estimate of increased risk (odds ratio [OR] 1.77; 95% CI, 1.14-2.75; P = .01). CONCLUSIONS: The present meta-analysis shows a significant association between high Lp(a) levels and the occurrence of venous thromboembolism in adults. Indeed, the detection of Lp(a) could be of clinical relevance for venous thromboembolism, especially among patients with absence of traditional and thrombophilic risk factors.