Cystatin C and modification of diet in renal disease (MDRD) estimated glomerular filtration rate differ during normal pregnancy

Background/Aims: Persons with occult-reduced estimated glomerular filtration rate (eGFR <60 ml/min/1.73 m2 detected by serum cystatin C but missed by creatinine) have high risk for complications. Among persons with preserved kidney function by creatinine-based eGFR (eGFRcreat >60 ml/min/1.73 m2), tools to guide cystatin C testing are needed. Methods: We developed a risk score to estimate an individual's probability of reduced eGFR by cystatin C (eGFRcys <60 ml/min/1.73 m2) in The Reasons for Geographic and Racial Differences in Stroke (REGARDS) study and externally validated in the Third National Health and Nutrition Examination Survey (NHANES III). We used logistic regression with Bayesian model averaging and variables available in practice. We assessed performance characteristics using calibration and discrimination measures. Results: Among 24,877 adults with preserved kidney function by creatinine, 13.5% had reduced eGFRcys. Older and Black participants, current smokers and those with higher body mass index, lower eGFRcreat, diabetes, hypertension and history of cardiovascular disease were more likely to have occult-reduced eGFR (p < 0.001). The final risk function had a c-statistic of 0.87 in REGARDS and 0.84 in NHANES. By risk score, 72% of occult-reduced eGFR cases were detected by screening only 22% of participants. Conclusions: A risk score using characteristics readily accessible in clinical practice can identify the majority of persons with reduced eGFRcys, which is missed by creatinine.

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Performance of Cystatin C– and Creatinine-Based Estimated Glomerular Filtration Rate Equations Depends on Patient Characteristics

Clinical Chemistry ◽

10.1373/clinchem.2015.243030 ◽

2015 ◽

Vol 61 (10) ◽

pp. 1265-1272 ◽

Cited By ~ 27

Author(s):

Jeffrey W Meeusen ◽

Andrew D Rule ◽

Nikolay Voskoboev ◽

Nikola A Baumann ◽

John C Lieske

Keyword(s):

Glomerular Filtration Rate ◽

Kidney Disease ◽

Glomerular Filtration ◽

Cystatin C ◽

Filtration Rate ◽

Estimated Glomerular Filtration Rate ◽

Patient Characteristics ◽

Transplant Recipients ◽

Ckd Stage ◽

Measured Gfr

Abstract BACKGROUND The Kidney Disease Improving Global Outcomes (KDIGO) guideline recommends use of a cystatin C–based estimated glomerular filtration rate (eGFR) to confirm creatinine-based eGFR between 45 and 59 mL · min−1 · (1.73 m2)−1. Prior studies have demonstrated that comorbidities such as solid-organ transplant strongly influence the relationship between measured GFR, creatinine, and cystatin C. Our objective was to evaluate the performance of cystatin C–based eGFR equations compared with creatinine-based eGFR and measured GFR across different clinical presentations. METHODS We compared the performance of the CKD-EPI 2009 creatinine-based estimated GFR equation (eGFRCr) and the newer CKD-EPI 2012 cystatin C–based equations (eGFRCys and eGFRCr-Cys) with measured GFR (iothalamate renal clearance) across defined patient populations. Patients (n = 1652) were categorized as transplant recipients (n = 568 kidney; n = 319 other organ), known chronic kidney disease (CKD) patients (n = 618), or potential kidney donors (n = 147). RESULTS eGFRCr-Cys showed the most consistent performance across different clinical populations. Among potential kidney donors without CKD [stage 2 or higher; eGFR >60 mL · min−1 · (1.73 m2)−1], eGFRCys and eGFRCr-Cys demonstrated significantly less bias than eGFRCr; however, all 3 equations substantially underestimated GFR when eGFR was <60 mL · min−1 · (1.73 m2)−1. Among transplant recipients with CKD stage 3B or greater [eGFR <45 mL · min−1 · (1.73 m2)−1], eGFRCys was significantly more biased than eGFRCr. No clear differences in eGFR bias between equations were observed among known CKD patients regardless of eGFR range or in any patient group with a GFR between 45 and 59 mL · min−1 · (1.73 m2)−1. CONCLUSIONS The performance of eGFR equations depends on patient characteristics that are readily apparent on presentation. Among the 3 CKD-EPI equations, eGFRCr-Cys performed most consistently across the studied patient populations.

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