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Abstract: PO0021

Anemia Following AKI After Non-Cardiac Surgery and Long-Term Outcomes: The NARA-AKI Cohort Study

Session Information

Category: Acute Kidney Injury

  • 101 AKI: Epidemiology, Risk Factors, and Prevention

Authors

  • Nishimoto, Masatoshi, Nara Kenritsu Ika Daigaku, Kashihara, Nara, Japan
  • Murashima, Miho, Nagoya Shiritsu Daigaku Daigakuin Igaku Kenkyuka Igakubu, Nagoya, Aichi, Japan
  • Kokubu, Maiko, Nara Kenritsu Ika Daigaku, Kashihara, Nara, Japan
  • Matsui, Masaru, Nara-ken Sogo Iryo Center, Nara, Nara, Japan
  • Eriguchi, Masahiro, Nara Kenritsu Ika Daigaku, Kashihara, Nara, Japan
  • Samejima, Ken-ichi, Nara Kenritsu Ika Daigaku, Kashihara, Nara, Japan
  • Akai, Yasuhiro, Nara Kenritsu Ika Daigaku, Kashihara, Nara, Japan
  • Tsuruya, Kazuhiko, Nara Kenritsu Ika Daigaku, Kashihara, Nara, Japan
Background

The aim of this study was to investigate whether acute kidney injury (AKI) is an independent predictor of anemia and whether anemia following AKI is a mediator of mortality after AKI.

Methods

This is a retrospective cohort study. Adults who underwent non-cardiac surgery from 2007 to 2011 were included. Those with obstetric or urological surgery, missing data for analyses, or preoperative dialysis were excluded. Subjects were followed until the end of 2015 or loss to follow-up. The exposure of interest was postoperative AKI defined by KDIGO criteria. The outcome variables were hematocrit values measured at 3, 6, and 12 months postoperatively and mortality. Associations between AKI and hematocrit or association between AKI and mortality were examined by multivariable linear regression or cox regression analyses, respectively. Data were adjusted for potential confounders.

Results

Among 6692 subjects, 445 (6.6%) developed AKI. Among those with postoperative data, AKI was independently associated with lower hematocrit values at 3, 6, and 12 months postoperatively, with coefficients [95% confidence interval] of −0.79 [−1.47 to −0.11], n=1750, −1.35 [−2.11 to −0.60], n=1558, and −0.91 [−1.59 to −0.22], n=2463, respectively. Higher stages of AKI and longer duration of AKI were associated with more severe anemia. AKI was associated with higher mortality after 3 months postoperatively with hazard ratio [95% confidence interval] of 1.54 [1.12 to 2.12]. Further adjustment with hematocrit values at 3 months attenuated the association (1.45 [1.05 to 2.00]). Mediation effect was significant (p=0.02) by mediation analysis.

Conclusion

AKI was an independent predictor of anemia following AKI. This might be due to permanent interstitial damage and impaired erythropoietin production. Higher mortality associated with AKI was at least partially mediated by anemia following AKI. Whether correction of anemia following AKI improves outcome of AKI requires further research.

Funding

  • Private Foundation Support