Development of an estimated glomerular filtration rate formula in cats.

Natalie C Finch,Harriet M Syme,Jonathan Elliott

doi:10.1111/jvim.15325

Natalie C Finch, Harriet M Syme + Show 1 more

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https://doi.org/10.1111/jvim.15325

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Abstract

BackgroundEstimated glomerular filtration rate (eGFR) formulas are routinely used in human patients to provide a more accurate evaluation of GFR compared to serum creatinine concentration alone. Similar formulas do not exist for cats.ObjectivesTo validate a prediction formula for eGFR in cats based on adjusting serum creatinine concentration.AnimalsClient‐owned cats with various levels of renal function.MethodsThe study was cross‐sectional. Glomerular filtration rate was determined by iohexol clearance. Variables including signalment, biochemical markers, and noninvasive measurements considered to represent surrogate markers of muscle mass were evaluated with the reciprocal of serum creatinine concentration in a multivariable regression model. The derived eGFR formula was subsequently tested in another group of cats and agreement with GFR assessed.ResultsThe formula was developed in 55 cats. Only a single morphometric measurement (pelvic circumference) along with the reciprocal of serum creatinine concentration (creatinine−1) independently predicted GFR in the final multivariate model. The derived eGFR formula was 0.408 + (243.11 × creatinine−1 [μmol/L]) ‐ (0.014 × pelvic circumference [cm]). When the formula was tested in another 25 cats it was not found to offer any advantage over creatinine−1 alone in its relationship with GFR (eGFR, R 2 = 0.44, P < .001 vs reciprocal of creatinine, R 2 = 0.45, P < .001). Furthermore, agreement between eGFR and GFR was poor.Conclusions and Clinical ImportanceAn eGFR formula for cats that adjusted serum creatinine concentration for a marker of muscle mass was developed. The formula did not provide a reliable estimate of GFR, and therefore, its routine use cannot be recommended.

Highlights

The morphometric measurement, pelvic circumference (PC), was the only significant measurement considered to be a surrogate marker of muscle mass for correcting the reciprocal of serum creatinine concentration to predict glomerular filtration rate (GFR) in a multivariable regression model
The most recently developed prediction formula for GFR in human patients is the chronic kidney disease (CKD)-EPI formula. Because this formula was developed in patients with decreased and normal renal function, it is considered appropriate for both populations
When the relationship between serum creatinine concentration and GFR was explored in the study in which the Modification of Diet in Renal Disease (MDRD) equation was developed, the R2 was 0.8,4 suggesting these formulas do offer some advantage over the use of serum creatinine concentration alone

Summary

Background

Estimated glomerular filtration rate (eGFR) formulas are routinely used in human patients to provide a more accurate evaluation of GFR compared to serum creatinine concentration alone. Objectives: To validate a prediction formula for eGFR in cats based on adjusting serum creatinine concentration. A single morphometric measurement (pelvic circumference) along with the reciprocal of serum creatinine concentration (creatinine−1) independently predicted GFR in the final multivariate model. When the formula was tested in another 25 cats it was not found to offer any advantage over creatinine−1 alone in its relationship with GFR (eGFR, R2 = 0.44, P < .001 vs reciprocal of creatinine, R2 = 0.45, P < .001). Conclusions and Clinical Importance: An eGFR formula for cats that adjusted serum creatinine concentration for a marker of muscle mass was developed. The formula did not provide a reliable estimate of GFR, and its routine use cannot be recommended

| INTRODUCTION

| MATERIALS AND METHODS

| RESULTS

Findings

| DISCUSSION