Cystatin C-based eGFR Offers Valuable Insights into Renal Function in HIV/AIDS Patients on ART: Study

According to the study, cystatin C-based eGFR exhibited a high specificity and a high positive likelihood ratio in the diagnosis of kidney disease among HIV/AIDS patients on ART. Cystatin C-based eGFR can be used as a confirmatory test.

"Cystatin C-based eGFR's specificity at 99.3% & a high positive likelihood ratio of 18.81 with a diagnostic accuracy of 90.7%," the researchers reported in BMC Nephrology. 

In clinical practice, estimated glomerular filtration rates (eGFR) measurement is the gold standard for assessing renal function the glomerular filtration rate is often determined from plasma creatinine. Previous studies have shown Cystatin C-based eGFR (Cys C) to be a better parameter for diagnosing impaired renal function. Cystatin C-based eGFR has been proposed as a potential renal function marker, but its use in patients with HIV/AIDS has not been well evaluated.

Against the above background, Enock Wekiya, Mildmay Uganda, Kampala, Uganda, and colleagues aimed to assess the clinical utility of Cystatin C-based eGFR in HIV-infected individuals on ART.

For this purpose, the researchers conducted a cross-sectional study on 914 HIV/AIDS patients on antiretroviral therapy attending Mildmay Uganda for care and treatment between January and March 2015. Particle-enhanced immunoturbidimetric assay was used to measure serum Cystatin C-based eGFR. Creatinine was analyzed using the enzymatic Creatinine PAP method, and creatinine clearance was calculated according to C&G.

The researchers reported the following findings:

· The sensitivity of Cystatin C-based eGFR was 15.1% with a specificity of 99.3%.

· The positive and negative predictive values were 70.0% and 91.2% respectively.

· The positive likelihood ratio was 18.81, and the negative likelihood ratio was 0.85.

· Cystatin C-based eGFR had a diagnostic accuracy of 90.7, and the area under the curve was 0.768.

In conclusion, the study showed that Cystatin C-based eGFR had a high specificity of 99.3% but a low sensitivity of 15.1%, implying that Cystatin C-based eGFR can be used as a confirmatory test, not as a screening test, a negative and positive predictive value of 91.2% and 70%, a high positive likelihood ratio of 21 and a negative predictive value 0.8 with a high diagnostic accuracy of Cystatin C based eGFR with the area under the curve of 0.77.

"While Inflammation can affect Cystatin C levels, leading to inaccuracies in eGFR calculations, in the study, we did not measure CRP, and thus future studies are needed to explore the impact of inflammation on Cystatin C-based eGFR results by considering including CRP testing in the study design," the researchers wrote.

Reference:

Wekiya, E., Mujuzi, G.P., Nakiyingi, J. et al. The clinical utility of cystatin C based eGFR in assessing renal function among HIV/AIDs patients on ART at Mildmay Uganda. BMC Nephrol 25, 144 (2024). https://doi.org/10.1186/s12882-024-03581-3