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Kidney Week

Abstract: TH-PO662

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

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
  • Katz, Ronit, University of Washington, Seattle, Washington, United States
  • Bansal, Nisha, Kidney Research Institute, Seattle, Washington, United States
  • Siscovick, David, University of Washington, Seattle, Washington, United States
  • Ix, Joachim H., UCSD, San Diego, California, United States
  • Shlipak, Michael, San Francisco VA Medical Center, San Francisco, California, United States
  • Rifkin, Dena E., UCSD, San Diego, California, United States
Background

Kidney function is typically assessed using serum creatinine. Cystatin C is an alternative marker of kidney function. The clinical significance of having a difference in estimated glomerular filtration rate (eGFR) by these 2 measures is unknown. We hypothesized that the magnitude of this difference is associated with frailty.

Methods

In 4101 community-dwelling older adults from the Cardiovascular Health Study (CHS) cohort, we investigated the cross-sectional association of the difference in eGFR by cystatin C vs. by creatinine (eGFRDiff) at baseline with prevalent frailty, using logistic regression, and the longitudinal association of eGFRDiff with incident frailty and mortality at 5 years, using Poisson regression. eGFR was calculated using CKD-EPI equations based on either measure (eGFRCr and eGFRCys respectively), and eGFRDiff was eGFRCys - eGFRCr. Frailty was assessed based on the Fried frailty score.

Results

Mean (±SD) age was 72 (±5) years, eGFRCr was 73 (±17) and mean eGFRDiff was -1.4 (range -68.0 to 70.6) mL/min/1.72m2. 39% were males, 5% African-American, 72% non-diabetics. Per 10-point increment in eGFRDiff, the prevalence of moderate frailty was 19% lower, and that of severe frailty was 36% lower, in fully adjusted model (Table 1). Higher eGFRDiff (per 10 mL/min/1.73m2) was associated with lower incidence rate ratio for moderate (IRR 0.93, 95%CI [0.87; 0.99]) and severe (IRR 0.59, 95%CI [0.47; 0.74]) frailty, as well as lower risk of mortality (IRR 0.65, 95%CI [0.57; 0.76], p<0.0001).

Conclusion

Those with a lower eGFRCys than eGFRCr were more likely to have prevalent frailty and were at higher risk for incident frailty and mortality. Considering eGFRDiff as a marker of patients’ functional status may be a useful clinical tool to assess important geriatric outcomes.

Association of eGFRDiff (per 10-point increment) with frailty at baseline
Outcome: Frailty (n = 2084)Moderately Frail (n=1832)Severely Frail (n=252)
 OR (95% CI)p valueOR (95% CI)p value
Unadjusted0.78 (0.74; 0.82)<0.00010.64 (0.58; 0.71)<0.0001
Fully adjusted *0.81 (0.76; 0.85)<0.00010.64 (0.57; 0.72)<0.0001

*adjusted for age, gender, race, body mass index, hypertension, diabetes, anti-hypertensives at baseline, cholesterol, smoking, chronic kidney disease stage by eGFRCr

Funding

  • Other NIH Support