In order to reduce

the bias inherited in observational studies, the multivariate adjusted or propensity score matching (PSM) adjusted odds ratios (ORs) instead of crude ORs were extracted for analysis if available. Postoperative AKI requiring renal replacement therapy (RRT) was viewed as a more severe form of postoperative JAK inhibitor AKI and was analyzed separately. Two authors independently conducted a systematic literature search for surgery, statin, and AKI in Medline (via PubMed) from inception to April 2013, and EMBASE from inception to April 2013. We used a keyword list combining three separate queries composed of medical subject heading (Mesh) and text word (tw) keywords for the search. The three queries were directed at population, exposure, and outcome of interest, respectively (see Appendix 1 for the full search term). We did not apply any restrictions on dates, type of article, language, sex, or age. A similar search strategy and search terms was repeated in EMBASE. In addition, reference lists of

potentially relevant reports and reviews were screened to identify other eligible studies. All titles and abstracts from the search were recorded into a file. Two reviewers (Dr. Pan and Dr. Lee) independently identified articles eligible for in-depth examination using the following pre-defined inclusion and exclusion criteria. Observational studies and clinical trials from the inception of the database until April 2013 were included if all of the following inclusion criteria were met: (i) patients receiving major surgery; (ii) use of any commercially available statins

before operation; and (iii) report of AKI HM781-36B purchase at any time after operation. Major surgery was defined as cardiac, thoracic, vascular, intra-abdominal, and retroperitoneal surgery. AKI was defined according to i) at least stage 1 of Acute Kidney Injury Network (AKIN) or stage ‘R’ of RIFLE stage,[48, 49] i.e. increase of the level of serum creatinine of greater than 0.3 mg/dL or greater than 50% from baseline; (ii) database codes of AKI at each study database; or (iii) AKI requiring RRT. RRT was defined as any type of renal support including haemodialysis, haemofiltration, haemodiafiltration, and peritoneal dialysis. Studies were excluded if any of the following exclusion criteria were met: (i) patients receiving renal transplantation and/or partial or total nephrectomy Loperamide operations; (ii) patients receiving endovascular procedures; (iii) publication types of review, meta-analysis, case reports, editorials, comments, and practice guidelines; and (iv) study types of animal studies or in vitro studies. When more than one publication from the same patient cohort existed, we included only the most recent publication that met the inclusion criteria. Any discrepancies of articles meriting inclusion or exclusion between reviewers were resolved by a consensus meeting of three authors. A summary of the study selection is given in Figure 1.