ubular cells by oxygen-free radicals and proinflammatory cytokines may be decreased by antiinflammatory effects of statins that inhibit tissue factor expression by macrophages and prevent the activation of nuclear factor-kB. Moreover, its nonlipid-lowering effect could be demonstrated within a few hours after statin therapy initiation. Although many clinical trials have shown that high-dose statins provide more clinical benefits, such as atorvastatin 80 mg can further reduce vascular risks compared with low-dose statin therapy, the threshold of statins to reduce the risks of CIN remains unknown. In this meta-analysis, all of the purchase SB366791 included trials were short-term high-dose statin therapy, two of which compared two different doses of statin in preventing CIN. We found that high-dose statin therapy significantly lowered the incident of CIN compared with low-dose statin therapy. These results were consistent with the previous studies that high-dose statin has been shown to be more potent to suppress platelet activity and inflammatory chemokines than low-dose statin therapy. The results of this meta-analysis are not in line with research from Zhang T et al, Zhang L et al and Pappy R et al which showed non-statistically significant reduction in the incidence of CIN with statin treatment from the pooled estimate for the randomized trials. In fact, Zhang T et al and Pappy R et al included both randomized and non-randomized trials in their meta-analysis, while the latter might lead to 15256538” potential bias because it was impossible to completely remove 12624814” interference of unknown confounding factors. The meta-analysis by Zhang L et al involved only 4 RCTs, which included an abstract that overlapped with participants included in a separate study by the same author. Therefore, to avoid including any individual participant more than once, abstract by the same author was excluded in our meta-analysis. Moreover, all of above three meta-analysis did not include two large scale studies published in recent days. Although the main conclusion in our meta-analysis was similar to that in the recent meta-analysis, these similar results shall be treated with cautious interpretation. First, in our metaanalysis, we found that statin was able to prevent CIN only in studies with lower quality, especially those which did not use of blinding, but not effective in high quality studies. This indicated that the results from the meta-analysis could not definite the effects of statins in preventing CIN. Second, pre-existing renal dysfunction was known to be an independent predictor of CIN that occured in up to 15% of patients with chronic kidney disease. 
However, subgroup analysis in risk group for CIN also weakened our findings. The studies that included patients with Statin Prevents Contrast-Induced Nephropathy pre-existing renal dysfunction found no preventive effect of statins. Multiple nonreversible pathogenetic mechanisms involved in advanced renal failure may attenuate the response for statins, especially for their vasodilatation and anti-inflammatory effects. In addition, although a higher serum level was expected in CKD patients, local drug concentration still might be compromised due to renal scar and structural impairment. So the safety, pharmacokinetics and permeability of various statins in CKD patients should be well evaluated in future studies. Third, N-acetylcysteine, a thiol-containing antioxidant, was a promising agent to prevent contrast induced nephropathy becaus
