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Kidney Week

Abstract: SA-PO106

Preoperative Serum Creatinine-to-Cystatin C Ratio and Risk of AKI After Cardiac Surgery

Session Information

Category: Acute Kidney Injury

  • 101 AKI: Epidemiology, Risk Factors, and Prevention

Authors

  • Koh, Hee Byung, Catholic Kwandong University International Saint Mary's Hospital, Incheon, Korea (the Republic of)
  • Kim, Hyo Jeong, Gangnam Severance Hospital, Seoul, Korea (the Republic of)
  • Kim, Hyung Woo, Yonsei University College of Medicine, Seodaemun-gu, Seoul, Korea (the Republic of)
  • Moon, Sung Jin, Catholic Kwandong University International Saint Mary's Hospital, Incheon, Korea (the Republic of)
  • Han, Seung Hyeok, Yonsei University College of Medicine, Seodaemun-gu, Seoul, Korea (the Republic of)
  • Yoo, Tae-Hyun, Yonsei University College of Medicine, Seodaemun-gu, Seoul, Korea (the Republic of)
  • Kang, Shin-Wook, Yonsei University College of Medicine, Seodaemun-gu, Seoul, Korea (the Republic of)
  • Park, Jung Tak, Yonsei University College of Medicine, Seodaemun-gu, Seoul, Korea (the Republic of)
Background

Postoperative acute kidney injury (AKI) is a serious complication after cardiac surgery, but risk stratification measures are limited. Decreased muscle mass is linked to negative outcomes, including kidney disease, in various clinical settings. More recently, the creatinine to cystatin C (Cr/Cys) ratio has shown correlation with muscle mass in several patients populations. This study aims to explore the association between preoperative serum Cr/Cys ratio and postoperative AKI in cardiac surgery patients.

Methods

Patients aged ≥18 years who underwent cardiac surgery at two tertiary hospitals between 2006 and 2020 were retrospectively evaluated. Their preoperative serum Cr/Cys ratios were categorized into quartiles. Primary outcomes were postoperative mild AKI (KDIGO stage 1) and moderate-severe AKI (KDIGO stage 2-3). Secondary outcome was length of hospital stay.

Results

Of the 2,354 enrolled patients (median age, 67.0 years; male, 65.2%), mild AKI and moderate-severe AKI were noted in 803 (34.1%) and 150 (6.4%) patients, respectively. Patients with higher Cr/Cys ratio had lower frequency of postoperative AKI and shorter lengths of hospital stay. Logistic regression analysis revealed that the odds ratios (ORs) [95% CI] for postoperative mild AKI and moderate-severe AKI decreased in a stepwise manner towards higher Cr/Cys ratio quartiles (mild AKI: Q2, 0.77 [0.61-0.97]; Q3, 0.75 [0.59-0.95]; Q4, 0.62 [0.49-0.79]; moderate-severe AKI: Q2, 0.67 [0.43-1.02]; Q3, 0.45 [0.28-0.73]; Q4, 0.54 [0.34-0.85] relative to the Q1, both P for trend <0.001). These associations were maintained after adjusting for confounding factors. Multivariable linear regression analyses revealed that patients in the 4th quartile of the Cr/Cys ratio had shorter hospital (-3.32 days, 95% CI, -5.34 to -1.30) stay than those in the 1st quartile.

Conclusion

Higher preoperative Cr/Cys ratios were associated with a lower risk of AKI development after cardiac surgery.