Oxidative stress biomarkers as predictors of cardiovascular disease

Evidence for the role of oxidative stress in the pathogenesis of cardiovascular disease (CVD) is primarily based on experimental and observational human studies. The aim of this review is to examine the observational longitudinal studies that have investigated the relationship between oxidative stress biomarkers and CVD. Fifty-one studies were identified with twenty-six of these measuring oxidized (Ox)-LDL, fifteen assessing myeloperoxidase, seven using lipid peroxidation measures and three quantifying protein oxidation. Results of studies using Ox-LDL have been equivocal with sixteen of the twenty-six studies reporting that this measure is predictive of cardiovascular events. These inconsistent results are not explained by differences in the study populations (primary or secondary CVD) or the type of assay used (auto or monoclonal antibodies). Six of the seven lipid peroxidation, and two of three protein oxidation studies found associations. Twelve of fifteen studies assessing the role of myeloperoxidase reported it to be predictive of CVD. However, issues surrounding the specificity of myeloperoxidase as a marker of oxidative stress and the small number of research groups reporting these results, limit this finding. In summary, the ability of oxidative stress biomarkers to predict CVD has yet to be established. Furthermore, it is important to note that the methods used to assess oxidative stress in these studies are indirect, and the evidence that the various methods actually reflect oxidative stress in vivo is limited.