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Kidney Week

Abstract: TH-PO661

The Difference Between eGFR by Cystatin C vs. Creatinine Provides Clinical Information About Frailty in SPRINT

Session Information

  • Geriatric Nephrology
    November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Geriatric Nephrology

  • 1100 Geriatric Nephrology

Authors

  • Potok, O. Alison, UCSD, San Diego, California, United States
  • Ix, Joachim H., UCSD, San Diego, California, United States
  • Shlipak, Michael, San Francisco VA Medical Center, San Francisco, California, United States
  • Katz, Ronit, University of Washington, Seattle, Washington, United States
  • Hawfield, Amret T., Wake Forest School of Medicine, Winston-Salem, NC, North Carolina, United States
  • Rocco, Michael V., Wake Forest School of Medicine, Winston-Salem, NC, North Carolina, United States
  • Ambrosius, Walter T., Wake Forest School of Medicine, Winston-Salem, NC, North Carolina, United States
  • Cho, Monique E., University of Utah, Salt Lake City, Utah, United States
  • Pajewski, Nicholas M., Wake Forest School of Medicine, Winston-Salem, NC, North Carolina, United States
  • Rastogi, Anjay, Division of Nephrology, Los Angeles, California, United States
  • Rifkin, Dena E., UCSD, San Diego, California, United States
Background

In prior studies, the discrepancy between the glomerular filtration rate (eGFR) estimated using either creatinine [eGFRCr] or cystatin C [eGFRCys] has been treated as measurement error related to kidney function. We propose instead that clinical information about frailty and muscle strength is contained in these differences. We examined the difference between eGFR by cystatin C and creatinine and its relationship to frailty, in cross-sectional and longitudinal analyses.

Methods

9092 SPRINT participants had baseline measures of serum creatinine and cystatin C. eGFRCr and eGFRCys were calculated using CKD-EPI equations, and eGFRDiff was defined as eGFRCys - eGFRCr. A 37-item frailty index (FI) included questionnaires, past medical history, cognitive tests and laboratory data (excluding albuminuria and eGFR). As defined in prior studies, frailty was FI > 0.21.

Results

Average (SD) was 68 (±9) years for age and was 73 (±23) for eGFRCys, 72 (±20) for eGFRCr, and 0.45 (±15) mL/min/1.73m2 for eGFRDiff. Compared to participants with minimal difference in eGFR, those with a substantially positive difference eGFRDiff (≥20 mL/min/1.73m2) were younger (64 vs. 68 years) and more likely to be male (77% vs. 64%). Those with a substantially negative eGFRDiff (≤ -20 mL/min/1.73m2) were more likely to be frail (OR=1.34 95%CI [1.11; 1.61], p<0.01 in fully adjusted model, Table 1), and were at higher risk for death (HR=1.64 95%CI [1.14;2.36] p=0.008).

Conclusion

In SPRINT, an eGFRCys estimate that was substantially less than an eGFRCr estimate was associated with underlying frailty. The difference between eGFRCys and eGFRCr may provide important information on functional status and prognosis that should be incorporated into clinical reasoning when evaluating these measures.

Association of eGFRDiff groups with frailty at baseline
Outcome: FrailtyNegative eGFRDiff (< - 20 mL/min/1.73m2) (n=226)eGFRDiff Reference (-20 to +20 mL/min/1.73m2) (n=1796)Positive eGFRDiff (≥ 20 mL/min/1.73m2) (n=103)
 OR (95%CI)p valueOR (95%CI)p valueOR (95%CI)p value
Unadjusted1.43 (1.20; 1.70)<0.0010 (ref) 0.54 (0.43; 0.67)<0.001
Fully adjusted *1.40 (1.15; 1.72)0.0010 (ref) 0.76 (0.60; 0.97)0.028

*adjusted for age, gender, race, education, body mass index, randomization arm, albuminuria, cardiovascular risk factors, chronic kidney disease stage

Funding

  • Other NIH Support