Application Of Estimation Formula Of Glomerular Filtration In Renal Function Evaluation

Background: No conventional creatinine- or cystatin C- based GFR(glomerular filtration rate) estimation equation performed consistently outstanding in the elderly Chinese in our previous studies. This research aimed to further evaluate the performance of some recently proposed estimation equations based on creatinine and cystatin C, alone or combined, in this specific population.Materials and Methods: The equations were validated in a population totaling 419 participants(median age, 68 [range, 60-94] years). The estimated GFR(e GFR) calculated separately by 10 equations was compared with the reference GFR(r GFR) measured by the 99mTc-DTPA renal dynamic imaging method.Results: Median serum creatinine, cystatin C and r GFR were 0.93mg/L, 1.13mg/L and 74.20 m L/min/1.73m2, respectively. The Chinese population developed creatinineand cystatin C-based(Cscr-cys) equation yielded the slightest median absolute difference(8.81 versus a range 9.53-16.32, p<0.05 versus CKD-EPIscr equation), highest proportion of e GFR within 15% and 30% of r GFR(P15 and P30, 55.13 and 85.44, p<0.05 and p<0.01 versus CKD-EPIscr equation) and least root-mean-square-error(RMSE, 14.87 versus a range 15.30-22.45) in the whole cohort. A substantial agreement of diagnostic consistency between e GFR and r GFR(with a kappa 0.61-0.80) was also observed with the Cscr-cys equation. Moreover, measures of performance in Cscr-cys equation were consistent across normal-mildly injured GFR strata and age ≤ 80 years individuals. Among all the creatinine- or cystatin C- based alone equations, elderly Chinese developed creatinine-based(CEscr) equation performed best in this specific population. Nevertheless, none of theequations achieved ideal manifestation in the moderately-severely GFR-injured or in the 80 years or older individuals.Conclusion: Cscr-cys equation appeared to be optimal in the elderly Chinese among the investigated equations. If cystatin C is not available, the CEscr equation is an acceptable alternative. A multi-center study with abundant subjects to develop apposite formula for the elderly Chinese is assumed to be essential.Background: Various equations based on serum creatinine or/and cystatin C, required further validation in a Chinese population. We compared the performance of six Chinese equations(Mascr, Peiscr, Macys, Ccys, Mascr-cys and Cscr-cys) with the CKD-EPI equations in multi-center Chinese subjects and evaluated their applicability in clinical practice.Methods: A total of 1522 adult patients from four different hospitals of China were enrolled in the study. 99mTc-DTPA renal dynamic imaging was used as the reference GFR(r GFR), and serum creatinine and cystatin C were measured by standardized assays. An optimal score system was implemented in the study.Results: The average r GFR of recruited subjects was 67.30±28.89 ml/min/1.73m2. All estimated GFR(e GFR) correlated well with r GFR. In accordance with Bland-Altman analysis, the Cscr-cys equations achieved optimal overall performance(score 14 versus 0-6), with least bias(median difference,-0.57 ml/min/1.73m2; median absolute difference, 8.83 ml/min/1.73m2), best precision(17.99 ml/min/1.73m2), highest accuracy[percentage of e GFR within 15%,30% and 50% of the r GFR(P15, P30 and P50; 49.7%, 78.7% and 91.8%, respectively); root-mean-square-error(RMSE, 16.28)]. The Ccys equation, a typical cystatin C based equation, was another well-behaved formula with an impressive performance. The Ma equations performed much poorer than the CKD-EPI equations. Consistent results can be observed in the GFR- /age- and sex-specific subgroups, while none equation yielded ideal accuracy in GFR<60 ml/min/1.73 m2 subgroup.Conclusion: The Cscr-cys equation appeared to achieve the best performance for GFR estimation in overall Chinese adult patients. However, further researches are warranted to improve the accuracy of available equations in GFR less than 60 ml/min/1.73 m2 individuals.