Acute kidney injury (AKI) after noncardiac surgery predicts anemia development, regardless of postoperative renal function, investigators reported at the American Society of Nephrology’s Kidney Week 2020 Reimagined virtual conference.
In the NARA-AKI study of 6692 nondialysis patients undergoing noncardiac surgery (excluding urological or obstetric surgery), AKI developed in 445 patients (6.6%). In adjusted models, AKI was independently associated with lower hematocrit values at 3, 6, and 12 months postoperatively compared with no AKI, regardless of change in estimated glomerular filtration rate. Higher stages of AKI and longer duration of AKI were associated with more severe anemia, Masatoshi Nishimoto, MD, of Nara Kenritsu Ika University in Kashihara, Nara, Japan, and colleagues reported.
Furthermore, postoperative AKI was significantly associated with a 54% higher risk for all-cause mortality after 3 months, and this risk attenuated to 45% after adjustment for hematocrit. The investigators found a significant 24.8% mediating effect of post-AKI anemia on mortality. Neither chronic inflammation nor surgery for malignancy explained the associations.
Permanent tubulointerstitial damage might impair erythropoietin production, Dr Nishimoto’s team suggested. They could not determine whether left ventricular hypertrophy induced by anemia was responsible for the higher mortality. The team encouraged future studies that probe whether anemia correction after AKI improves outcomes.
Nishimoto M, Murashima M, Kokubu M, et al. Anemia following acute kidney injury after non-cardiac surgery and long-term outcomes: the NARA-AKI cohort study. Presented at: Kidney Week 2020 Reimagined, October 19-25, 2020. Poster PO0021.