ESTIMATED GLOMERULAR FILTRATION RATE IN KIDNEY TRANSPLANT RECIPIENTS: WHICH EQUATION PERFORMS BETTER?

Introduction:

It is crucial to assess kidney allograft function by monitoring the glomerular filtration rate (GFR) because it is a predictor of long-term graft survival. While numerous studies globally have investigated GFR monitoring in kidney transplant recipients (KTRs), research within the Vietnamese population remains limited, leaving the most accurate estimated GFR (eGFR) equation for KTRs uncertain. This study aimed to evaluate the performance of five established eGFR equations (MDRD, Asian modified CKD–EPI, CKD–EPI SCysC 2012, CKD–EPI SCr 2021, and CKD–EPI SCr–SCysC 2021) in the Vietnamese population.

Methods:

This cross-sectional study, which included 299 Vietnamese individuals from the Urology and Biochemistry Department of Cho Ray Hospital, was performed between January 2014 and February 2022. All participants who were KTRs had stable kidney function, defined as a GFR variation of no more than 20% over a 3-month period, were enrolled in the study after meeting the exclusion criteria. During this study, measured GFR (mGFR) determined using technetium-99m-diethylenetriaminepentaacetate (99mTc–DTPA) renal dynamic scintigraphy. The performances of the five eGFR equations were compared based on bias, P30 accuracy, absolute accuracy, precision, root mean square error (RMSE), concordance correlation coefficient (CCC), and Pearson's correlation coefficient (r), along with their 95% confidence intervals (CIs).

Results:

The study included a total of 299 KTRs. The median age was 39.00 years (31.00–48.50). The mean (SD) mGFR was 60.42 (16.00) mL/min/1.73 m2. The participants were divided into two subgroups based on mGFR values: 48.8% (146) had mGFR < 60 mL/min/1.73 m2, and 51.2% (153) had mGFR ≥ 60 mL/min/1.73 m2. Among the equations, CKD–EPI SCr–SCysC 2021 showed the best performance. The values for median bias, P30 accuracy, absolute accuracy, precision, RMSE, CCC, and r were: 2.57 [1.22; 3.55] mL/min/1.73 m2, 87.6% [83.3; 90.6], 10.0% [8.3; 11.7], 11.29 [9.57; 13.40] mL/min/1.73 m2, 11.54 [10.42; 12.92], 0.787 [0.737; 0.828], and 0.810 [0.759; 0.850], respectively. However, the MDRD equation did not show significantly lower precision and accuracy than the CKD–EPI SCr–SCysC 2021 equation. Both Bland–Altman and Deming regression plots indicated that all eGFR equations tended to overestimate GFR, except for the CKD–EPI SCysC 2012 equation (Figure 1 and Figure 2). Additionally, all five equations demonstrated improved accuracy in the mGFR ≥ 60 mL/min/1.73 m2 subgroup compared to the mGFR < 60 mL/min/1.73 m2 subgroup.

Conclusions:

Our findings suggest that the CKD–EPI SCr–SCysC 2021 equation is the most precise and accurate eGFR equation among those studied in Vietnamese KTRs. Therefore, we recommend this equation for routine clinical practice. However, the study has some limitations, including a relatively small sample size, the use of a non-gold standard for the mGFR measurements, and non-GFR factors affecting SCr and/or SCysC were not fully assessed or excluded. Further research and validation are needed to confirm these findings.

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.