Comparisons between validated estimated glomerular filtration rate equations and isotopic glomerular filtration rate in HIV patients

Abstract

Objective: Understanding how best to measure renal function in HIV-infected patients is critical because estimated glomerular filtration rate (eGFR) in HIV-infected patients can be affected by ethnicity and body composition. We validated the available eGFR equations and compared them to the plasma Tc-diethylenetriaminepentaacetic acid (Tc-DTPA) clearance in HIV-infected patients.

Design: Test of diagnostic accuracy.

Methods: One hundred and ninety-six HIV-infected patients underwent measuring of Tc-DTPA plasma clearance, five creatinine-based eGFR equations, cystatin-C GFR, and 24-h urine creatinine clearance (CrCl).

Results: Mean (SD) Tc-DTPA GFR was 117.7 ± 29.2 ml/min per 1.73 m. The re-expressed Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), re-expressed MDRD formula with Thai racial correction factor, Thai eGFR equation, Cockcroft-Gault equation, cystatin-C GFR, and 24-h urine CrCl underestimated the reference GFR. The bias estimated by the mean of differences (SD) for the re-expressed MDRD equation, CKD-EPI, re-expressed MDRD formula with Thai racial correction factor, Thai eGFR, Cockcroft-Gault equation, cystatin-C, and 24-h urine CrCl can be expressed as 18.9 ± 27.3, 11.1 ± 25.5, 6.2 ± 28.8, 15.4 ± 27.0, 30.4 ± 28.0, 3.2 + 36.1, and 5.0 ± 12.1 ml/min per 1.73 m, respectively.

Conclusion: The available eGFR equations underestimated GFR in HIV-infected adults. However, the eGFR by cystatin-C GFR was the most precise and accurate. Among creatinine-based eGFR equations, re-expressed MDRD formula with Thai racial correction factor was the most precise and accurate. The racial factor for each ethnicity is important and the existing eGFR equation should be validated before using it in the HIV population.

Conflict of interest statement

Conflicts of interest

All authors declare that there are no conflict of interest.

Figures

Figure 1

Bland-Altman plots of eGFR values calculated by different equations and the reference GFR which was used to show the disagreement between the equation and the reference. The mean bias and ± 1.96 SD are represented by the horizontal lines. The disagreement of different equations [A; re-expressed MDRD equation, B; CKD-EPI equation, C; re-expressed MDRD equation with Thai racial factor correction, D; Thai eGFR equation, E; Cockcroft & Gault, F; cystacin C GFR, and G; CrCL by 24 hr urine] are shown by the regression trend of the difference and the mean bias of the eGFRs towards the reference GFR.