Postoperative Anemia Is Associated with Acute Kidney Injury in Patients Undergoing Total Hip Replacement Arthroplasty: A Retrospective Study

Abstract

BACKGROUND: Chronic and acute anemia are both correlated with an increased risk of injury to major organs, such as the brain, heart, and kidney. We evaluated the association between postoperative anemia (hemoglobin [Hb] < 10 g/dL) and acute kidney injury (AKI) in patients undergoing total hip replacement arthroplasty (THRA). METHODS: Patients who underwent THRA between January 2005 and February 2013 were retrospectively reviewed. We divided patients into 2 groups: Hb < 10 (n = 938) and Hb ≥ 10 (n = 1529). They were then categorized according to changes in plasma creatinine concentration within 48 hours of THRA using Acute Kidney Injury Network criteria. To evaluate the association between postoperative anemia and postoperative AKI, an inverse-probability-of-treatment weighted method was used and both univariate and multivariable analyses were performed. RESULTS: Postoperative anemia was significantly associated with postoperative AKI (multivariate odds ratio, 2.036; 95% confidence interval, 1.369-3.028; P < 0.001; inverse probability-of-treatment weighted odds ratio, 1.817; 95% confidence interval, 1.169-2.826; P = 0.011). In patients with a normal glomerular filtration rate, postoperative AKI was also related to postoperative anemia (P = 0.010). CONCLUSIONS: Postoperative anemia was associated with postoperative AKI after THRA. Although our study was limited by its retrospective design, our observation suggests that postoperative anemia may play a role in postoperative AKI.