Anemia following acute kidney injury after noncardiac surgery and long-term outcomes: the NARA-AKI cohort study.

"CONFLICT OF INTEREST STATEMENT None declared. The results presented in this article have not been published previously in whole or part, except in abstract form."

"FUNDING This study was supported by Nara Medical University Grant-in-Aid for Young Scientists and a grant from the Kidney Foundation, Japan (grant no. JKFB 19-10)."

"The NARA-AKI cohort study is a single-center, retrospective study. Inclusion criteria were subjects ≥18 years of age who underwent noncardiac surgery under general anesthesia from April 2007, when electronic medical records started at Nara Medical University Hospital, to December 2011. Exclusion criteria were those who underwent obstetric surgery (as serum creatinine levels decrease during pregnancy due to hemodilution and criteria for AKI are not validated in pregnant women) or urological surgery (as an increase in creatinine due to nephrectomy or ureteral manipulation could have different underlying mechanisms from other postoperative AKI), preoperative dialysis or those with missing data for serum creatinine within 1 month before and 1 week after surgery. If subjects underwent multiple surgeries during the study period, then only the first eligible surgery was considered. Subjects were followed through the end of 2015 or loss to follow-up. The hematocrit value was considered to be an indicator of anemia. The study protocol and waiver of consent were approved by the Nara Medical University Ethics Committee (approval no. 1208 and no. 1208-2 for amendment). This study waived the requirement for written informed consent due to its retrospective nature. Rather, research content has been included on the web page of our department (http://nephrology.naramed-u.ac.jp/research/clinical.html). This study was conducted in accordance with the Declaration of Helsinki. The study was registered in the University Medical Information Network (UMIN000037141)."