pathy, nephrotoxic, and, contrastinduced nephropathy and contrast-associated nephropathy. For the theme “statin”, statin, atorvastatin, rosuvastatin, cerivastatin, simvastatin, 
pravastatin, lovastatin, Hydroxymethylglutaryl-CoA reductase inhibitors and HMG-CoA reductase inhibitors were used. Appendix S1 shows the detailed search method. We did not restrict by language or type of article. To KU-55933 biological activity identify other relevant studies, we manually scanned reference lists from identified trials and review articles, and we also searched conference proceedings. We requested original data by directly contacting authors. dose of 80 mg or 40 mg) versus low-dose statin treatment or placebo. Studies that incorporated NAC were included only if both arms were administered NAC; studies reported the incidence of contrast-induced nephropathy in both arms. We did not restrict eligibility according to kidney function. The primary outcome measure was the development of contrast-induced nephropathy, defined as an increase in baseline serum creatinine level of 25% or an absolute increase of 44 mmol/L within 2 to 5 days after the exposure to contrast medium. Secondary outcome measures were need for dislysis, in-hospital mortality and length of hospital stay. Data extraction and quality assessment Data were collected independently by 2 reviewers. Extracted data included patient characteristics; inclusion criteria; type and dose of contrast media; protocol for the treatment of statins; periprocedural hydration protocol and specific definition of CIN. Quality assessment was judged on concealment of treatment allocation; similarity of both groups at baseline regarding prognostic factors; eligibility criteria; blinding of outcome assessors, care providers, and patients; completeness of follow-up; and intention-to-treat analysis. We quantified study quality by using the Jadad score. A third reviewer adjudicated any disagreement about extracted data.Moreover, heterogeneity across trials was evaluated with I2 statistic, which defined as I2.50%. If heterogeneity existed, a random-effect model was used to assess the overall estimate. Otherwise, a fixed-effect model was chosen. We assessed for potential publication bias by using Begg funnel plots of the natural log of the relative risk versus its standard error. To further detect and evaluate clinically significant heterogeneity, we also a priori decided to perform several subgroup analyses to identify potential differences in treatment across the trials. Subgroup analysis was conducted based on renal function in participants at baseline, the control group property, the addition of NAC, and Jadad study quality score. All tests were twotailed and a P value less than 0.05 was regarded as significant in this meta-analysis. Results Selected studies and characteristics We identified 322 potentially relevant citations from the initial literature search. After independently reviewing the title and abstract of all potential articles, 34 articles were considered of interest and reviewed in full-text. Of these, 27 were excluded from the meta-analysis. Although the study carried out by Acikel Sadik et al did not provide data on the incidence of CIN, we requested it by directly contacting the author. Therefore, seven randomized controlled studies with a total of 1,399 patients with undergoing radiocontrast-related procedures were identified and analyzed. Our search strategy is outlined in 5 Statin Prevents Contrast-Induced Nephropathy diff