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Abstract: TH-PO898

Discordances Between Creatinine and Cystatin C-Based eGFR and Adverse Clinical Outcomes in Routine Clinical Practice

Session Information

Category: CKD (Non-Dialysis)

  • 2201 CKD (Non-Dialysis): Epidemiology‚ Risk Factors‚ and Prevention

Authors

  • Fu, Edouard, Brigham and Women's Hospital, Boston, Massachusetts, United States
  • Carrero, Juan Jesus, Karolinska Institutet, Stockholm, Stockholm, Sweden
  • Sang, Yingying, Johns Hopkins University, Baltimore, Maryland, United States
  • Evans, Marie, Karolinska Institutet, Stockholm, Stockholm, Sweden
  • Inker, Lesley Ann, Tufts Medical Center, Boston, Massachusetts, United States
  • Levey, Andrew S., Tufts Medical Center, Boston, Massachusetts, United States
  • Coresh, Josef, Johns Hopkins University, Baltimore, Maryland, United States
  • Grams, Morgan, Johns Hopkins University, Baltimore, Maryland, United States
Background

The 2021 NKF-ASN Task Force recommended increased use of cystatin C-based eGFR equations. Discordances can occur between eGFRcr and eGFRcys, since creatinine and cystatin C have different non-GFR determinants. Currently, it is unknown how common and large these discordances are in routine clinical practice, and whether discordances predict adverse clinical outcomes. In Sweden, routine cystatin C testing has been available for over a decade.

Methods

We used data from the SCREAM project, which covers the healthcare of Stockholm region. We identified adults who, during 2011-2018, undertook outpatient tests of IDMS calibrated creatinine and cystatin C on the same day. eGFRcr and eGFRcys were calculated with the 2021 and 2012 CKD-EPI equations. Multivariable Cox proportional hazards regression was used to calculate hazard ratios for quartiles of discordance between eGFRcys and eGFRcr, and the outcomes AKI, kidney failure with replacement therapy (KFRT), major adverse cardiovascular events (MACE) and death.

Results

Of 1,570,592 people with eGFRcr, 13% also had routine eGFRcys. We included 158,663 participants (mean age 62 years, 48% women, mean eGFRcr 80 and eGFRcys 73 ml/min/1.73/m2) with both tests on the same day. Discordances were common, with eGFRcys in most cases being lower than eGFRcr. Patients with lower eGFRcys than eGFRcr were older, and more often female, with hypertension, diabetes or cardiovascular disease. Larger discordances were observed among patients with higher eGFRcr and UACR. Patients whose eGFRcys was lower than eGFRcr were at higher risk of all study outcomes. Conversely, patients whose eGFRcys was higher than their eGFRcr were at lower risks (Table). Similar findings were observed within subgroups of eGFR categories, age, sex, and comorbidities.

Conclusion

Integration of cystatin C testing into routine clinical practice in the Stockholm region showed many patients with a discordance between eGFRcys and eGFRcr. Lower eGFRcys than eGFRcr consistenly identified patients at higher risk of multiple outcomes.