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Assessing glomerular filtration rate in hospitalized patients: a comparison between CKD-EPI and four cystatin C-based
Alfonso Segarra1, Judith de la Torre, Natalia Ramos
1Nephrology Department, Hospital Universitari Vall d'Hebrón, Passeig de la Vall d'Hebron, 119 to 129. 08035 Barcelona, Spain. alsegarr@gmail.com
Insights
Cystatin C-based equations are more accurate for estimating glomerular filtration rate (GFR) in hospitalized patients, especially those with malnutrition or reduced body surface area. These equations are less affected by nutritional status than the CKD-EPI equation.
Area of Science:
- Nephrology
- Clinical Chemistry
- Epidemiology
Background:
- Accurate estimation of Glomerular Filtration Rate (GFR) is crucial for managing hospitalized patients.
- Existing GFR estimation equations may have limitations in diverse patient populations.
Purpose of the Study:
- To validate the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and four cystatin C (CysC)-based equations for GFR estimation in hospitalized individuals.
- To compare the accuracy of these equations against measured GFR (mGFR) using iohexol clearance.
Main Methods:
- Cross-sectional study of 3114 hospitalized patients.
- Evaluated CKD-EPI and four CysC-based equations (varying in included variables: CysC alone, CysC + gender, CysC + age, gender, race, CysC + age, gender, race, creatinine).
- Compared equation estimates against GFR measured by iohexol clearance; collected clinical, biochemical, and nutritional data.
Main Results:
- The CysC equation including age, gender, and race (equation 3) overestimated GFR (bias 7.4 ml/min per 1.73 m(2)).
- Creatinine-based equation errors were linked to muscle mass and nutritional status.
- CKD-EPI adequately estimated GFR in patients without malnutrition or reduced body surface area.
- CysC-based equations (2 and 4) provided more precise GFR estimates in patients with malnutrition, reduced body surface area, or muscle mass loss (biases 1 and 1.3 ml/min per 1.73 m(2)) compared to CKD-EPI (bias 5.9 ml/min per 1.73 m(2)).
Conclusions:
- Cystatin C-based equations, specifically those including gender or age, gender, and race, are more suitable for estimating GFR in hospitalized patients.
- These CysC equations demonstrate greater independence from patient nutritional status and muscle mass compared to the CKD-EPI equation.
- The findings support the use of specific CysC equations for improved GFR assessment in the hospital setting.
Background And Objectives:
A specific method is required for estimating glomerular filtration rate GFR in hospitalized patients. Our objective was to validate the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and four cystatin C (CysC)-based equations in this setting.
Design, Setting, Participants, & Measurements:
This was an epidemiologic, cross-sectional study in a random sample of hospitalized patients (n = 3114). We studied the accuracy of the CKD-EPI and four CysC-based equations--based on (1) CysC alone or (2) adjusted by gender; (3) age, gender, and race; and (4) age, gender, race, and creatinine, respectively--compared with GFR measured by iohexol clearance (mGFR). Clinical, biochemical, and nutritional data were also collected.
Results:
The CysC equation 3 significantly overestimated the GFR (bias of 7.4 ml/min per 1.73 m(2)). Most of the error in creatinine-based equations was attributable to calculated muscle mass, which depended on patient's nutritional status. In patients without malnutrition or reduced body surface area, the CKD-EPI equation adequately estimated GFR. Equations based on CysC gave more precise mGFR estimates when malnutrition, extensive reduction of body surface area, or loss of muscle mass were present (biases of 1 and 1.3 ml/min per 1.73 m(2) for equations 2 and 4, respectively, versus 5.9 ml/min per 1.73 m(2) for CKD-EPI).
Conclusions:
These results suggest that the use of equations based on CysC and gender, or CysC, age, gender, and race, is more appropriate in hospitalized patients to estimate GFR, since these equations are much less dependent on patient's nutritional status or muscle mass than the CKD-EPI equation.
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