Homocysteine and peripheral arterial disease: systematic review and meta-analysis

To evaluate homocysteine (Hcy) levels in patients with peripheral arterial disease (PAD) as compared to unaffected controls, and to review the clinical effects of therapy aimed at lowering homocysteine in PAD patients.

MEDLINE, EMBASE and Cochrane databases were searched from 1950 to December 2007. We selected observational studies and trials that evaluated Hcy levels in patients with PAD compared to unaffected controls. We also included trials on the effect of Hcy-lowering therapy (folate supplementation) in PAD patients. Continuous outcomes were pooled in a random effects meta-analysis of the weighted mean difference between comparator groups.

We retrieved 33 potentially suitable articles from our search. Meta-analysis of 14 relevant studies showed that Hcy was significantly elevated (pooled mean difference +4.31micromoll; 95% C.I. 1.71, 6.31, p<0.0001 with significant heterogeneity) in patients with PAD compared to controls. As all 14 studies consistently demonstrated raised plasma Hcy levels in PAD patients, the significant heterogeneity in this meta-analysis probably arises from differences in the degree of Hcy elevation. The effect of folate supplementation on PAD was tested in eight clinical trials but clinically important end points were inconsistently reported.

Patients with PAD have significantly higher Hcy levels than unaffected controls. However, we did not find any robust evidence on clinically beneficial effects of folate supplementation in PAD.