Performance Of Glomerular Filtration Rate Estimation Equations In Southern Chinese Han Patients With Chronic Kidney Disease

Objective:To evaluate the performance of glomerular filtration rate estimation equations based on serum creatinine ?Scr? or/and cystatin C ?Cys C? in Chinese patients with chronic kidney disease ?CKD?, we compared the agreements of these equations with the standardized glomerular filtration rate ?sGFR? obtianed with Technetium-^99m diethylene triamine pentaacetic acid (^99mTc-DTPA) renal dynamic imaging.Methods:Based on sGFR obtained with ^99mTc-DTPA renal dynamic imaging and standardized by body surface area ?BSA?,236 southern Chinese Han patients with CKD in the Second Affiliated Hospital of Nanchang University in April 2014 to September 2015 were enrolled in this study and their age, sex, height, weight, BSA and other basic information were collected. Scr was determined by the enzymatic method. Cys C was determined by particle-enhanced turbidmetric immune assay ?PETIA? method. The GFR was estimated by six creatinine-based equations ?the calibrated CG equation, simplified MDRD equation, modified MDRD equation for Chinese CKD disease, IDMS-MDRD equation, CKD-EPI equation, EPI-Asian equation?, eight Cys C based equations ?Hoek, Orebro, Le Brican, Filler, Larsson, Grubb, Rule, CKD-EPI ?2012Cys C?? and two equatios based on Scr and Cys C ?Collaborative Group of China eGFR subjects eauation and CKD-EPI?2012Cys C/Cr? equation?. The estimated GFR were compared with the sGFR.Results:1. In 236 cases of Chinese patients with CKD, the median absolute diffrence, median absolute percentage difference of Hoek equation were smaller than other equations?P< 0.001?. Correlation analysis revealed eGFR of these equations were highly correlated with sGFR?r> 0.79?, especially the eGFR of CKD-EPI ?2012Cys C/Cr? equation and CKD-EPIcr equation ?r= 0.839?. The 30% accuracy, the accuracy of CKD stage 2,3 and overall staging accuracy of Le Brican equation were higher than other equations?P< 0.001?. The 30% accuracy of Hoek equation ?P<0.001?was equal with Le Brican equation?P30= 0.64?. The accuracy of CKD stage 4 of Filler equation was higher than other equations?P< 0.001?.2. In female CKD patients, there were no significant difference between eGFR of Orebro equation, Le Bricon equation and Filler equation with sGFR ?P> 0.05?. The median difference, median percentage difference, median absolute difference and median absolute percentage difference of Hoek equation were smaller than other equations?P< 0.001?. Correlation analysis revealed eGFR of these equations were highly correlated with sGFR ?r> 0.8?, especially the eGFR of EPI-Asian equation and CKD-EPIcr equation ?r= 0.853?. The 30% accuracy and staging accuracy of of Hoek equation was higher than other equations?P< 0.001?.In male CKD patients, there were no significant difference between eGFR of Orebro equation and sGFR ?P= 0.903?. The median difference, median percentage difference, median absolute difference and median absolute percentage difference of Hoek equation were smaller than other equations?P< 0.001?. Correlation analysis revealed eGFR of these equations were highly correlated with sGFR?r> 0.79?, especially the eGFR of Collaborative Group of China eGFR subjects equation ?r 0.837?. The 30% accuracy of Hoek equation was higher than other equations?P< 0.001?. The staging accuracy of Le Bricon was higher than other equations?P< 0.005?.3. In CKD patients under 75 years old, there were no significant difference between eGFR of Orebro equation, Le Brican equation and Filler equation with sGFR ?P> 0.05?. The median difference, median percentage difference, median absolute difference and median absolute percentage difference of Hoek equation were smaller than other equations?P< 0.001?.In CKD patients under 45 years old, correlation analysis revealed eGFR of these equations were highly correlated with sGFR?r> 0.7?, especially the eGFR of simplified MDRD equation ?r= 0.859?. There was no significant difference among the 30% accuracy and the staging accuracy among these equations?P> 0.05?.In CKD patients from 45 years old to 59 years old, correlation analysis revealed eGFR of most equations were highly correlated with sGFR ?r> 0.8? especially the eGFR of Collaborative Group of China eGFR subjects equation ?r=0.851?. The 30% accuracy and staging accuracy of Hoek equation was higher than other equations?P< 0.001?.In CKD patients from 60 years old to 74 years old, correlation analysis revealed eGFR of these equations were highly correlated with sGFR?r> 0.7?, especially the eGFR of Collaborative Group of China eGFR subjects equation and CKD-EPI?2012Cys C/Cr? equation ?r= 0.839?. The 30% accuracy and staging accuracy of Hoek equation was higher than other equations?P< 0.001?.In CKD patients over 75 years old, the median difference, median absolute difference of Grubb equation were smaller than other equations?P< 0.05?. The median percentage difference of CKD-EPI ?2012Cys C? equatio?Filler equation were smaller than other equations?P< 0.001?. Correlation analysis revealed eGFR of equations based on Scr and equations based on Scr and Cys C were highly correlated with sGFR ?r> 0.7?, especially the eGFR of simplified MDRD equation and IDMS-MDRD equation?r= 0.802?, while eGFR of equations based only on Cys C were moderate correlated with sGFR?0.5< r< 0.69?. There were no significant difference among the 30% accuracy and staging accuracy among these equations?P> 0.05?.4. In the high level subgroup with a sGFR?60ml/min/1.73m², the median difference, median percentage difference of CKD-EPI?2012cys C/Cr? equation were smaller than other equations?P< 0.001?. Correlation analysis revealed eGFR of these equations were weekly correlated with sGFR ?r< 0.4? and the eGFR of CKD-EPI?2012cys C/Cr? equation was more strongly correlated with sGFR than other equations, while there was no significant difference between eGFR of CG/BSA equation and sGFR. There were also no significant difference among the 30% accuracy of these equations?P> 0.05? and the staging accuracy of CKD-EPI?2012Cys C/Cr? equation was higher than other equations?P< 0.001?.In the low level subgroup with a sGFR< 60ml/min/1.73m², the median absolute diffrence, median absolute percentage difference of Hoek equation were smaller than other equations?P< 0.001?. The median diffrence, median percentage difference of Filler equation were smaller than other equations?P< 0.001?. Correlation analysis revealed eGFR of these equations were highly correlated with sGFR ?r> 0.7?. The 30% accuracy of Hoek equation was higher than other equations?P< 0.001?.The staging accuracy of Le Bricon was higher than other equations?P< 0.001?.5. Bland-Altman plot analysis demonstrated that in the whole, between genders and across different age groups as well as in the low level subgroup with a sGFR< 60ml/min/1.73m², the eGFR of Rule equation was more consistent with sGFR than other equations. While in the high level subgroup with a sGFR? 60ml/min/1.73m², the eGFR of Hoek equation was more consistent with sGFR than other equations. Conclusions:1. In southern Chinese Han patients with CKD under 75 years old and low level subgroup with a sGFR< 60ml/min/1.73m², Hoek equation performed better in deviation, correlation,30% accuracy, staging accuracy and 95% consistency limits than ?or not inferior to? other equations, which can be used as the first choice to estimate GFR.2. In southern Chinese Han patients with CKD who has a sGFR? 60 ml/min/1.73m², CKD-EPI?2012Cys C/Cr? equation performed better in deviation, correlation,30% accuracy, staging accuracy and 95% consistency limits than ?or not inferior to? other equations, which can be used as the first choice to estimate GFR.